My assessment of your situation is basically that you suffer from an energetic imbalance. I have had periods during which I experienced similar states, and I am still prone to them nowadays, but I think that I am better at handling them when they happen.

See if these descriptions resonate with you:

• you feel that there is an excess of energetic activity
• you feel that chi / energy is volatile, explosive
• moving energy might be pleasurable at first, but as it becomes more volatile it also becomes more scary, like everything is changing too quickly
• you sometimes feel your head spinning very fast, and you think very many things very intensely
• you are prone to euphoria and great flashes of energy
• it's like moving through a floor that is permanently shifting, and trapped with geisers (you sometimes press somewhere and WOOSH)

The key word is probably "volatile," in all it's meanings:

• evaporating rapidly; passing off readily in the form of vapor.
• tending or threatening to break out into open violence; explosive.
• changeable; mercurial; flighty: a volatile disposition.
• tending to fluctuate sharply and regularly.
• fleeting; transient.

If it seems to you that this fits with what you are experiencing, then you may be interested in what I have to say this kind of energy imbalance. In my case I don't experience this kind of imbalance all the time. It seems to me that I alternate between three or four kinds of imbalances, two could be said to be of a "depressive" kind, and two of a "euphoric" kind, and the experience I have just alluded to is of the latter kind. So my situation is different than yours in that this isn't happening all the time.

The general advice I have received is very helpful: do grounding activities. Here something calm like manual work (DIYing, knitting, fixing things, etc) works quite well, but also exercising for a long session.

In terms of practices, anything that increases yin factors and downward flow is very helpful. Working with the lower part of the body: the legs, the abs, the feet, ankles and knees (at this point I always like to reference "The three amigos of rooting", which have helped me during a particularly difficult phase).

These two things are good to balance things out, they serve to mitigate the problem, though I don't think that they can solve it in a definite way.

So now to the core of the matter: what is happening? I hesitated whether to go into this, because my response is mainly conjectural, don't make the mistake of interpreting it as advice when it is actually too theoretical to serve as such.

My conjecture is that there is something intentional happening under the hood at some point in the process, something subtle and not easy to see, which gives the process momentum up to the point of imbalance.

This conjecture was formed from the following experience, which happens repeatedly when I get into one of these "volatile" phases. During such a phase, stuff "comes loose" very easily: if there is a bit of tension there, then all it takes is for me to focus on it for a little while, and it will start "breaking apart." This is followed by pleasure and relief at first, but this pleasure is accompanied/made of increasing energy, and this increased energy promotes even more effective and faster "breaking apart" of tense spots in the body, which in turn come loose and cause an increase in energy on their own.

This positive feedback loop accelerates and feeds itself, and very quickly the feeling of pleasure is replace with a sense of thrill, and if the process becomes too strong, thrill is replaced with anxiety and fear, which injects even more energy into the process and feeds it more, except at this point things are no longer pleasant at all.

At the very extreme of the process (at least the most extreme I have personally experienced it), it feels a bit like being raped by the universe. For instance, it is impossible to be in a public place because of the noise, as things that would usually be filtered such as banging of tableware are now felt banging my ear drums in the most intrusive of ways. Here I have reached extreme imbalance.

I have tried to be impartial in describing this process, but already in the way I have described it, you might think that maybe, just maybe, there is a way out. [1] Again I should warn you that not only my description of the process is itself somewhat theoretical (because although I have had the experiences above, I am of course not certain I am describing them in the most skillful way), and I have only been able to apply my "solution" two or three times, but if I am not mistaken then there is a specific point where it is possible to intervene in the process somewhat:

When something comes loose, or flows explosively from one place to another, pay attention to the quality of the sensations immediately as they happen; there is an energetic shit, the area feels energized, tingling, volatile, a bit like it was "on fire." I personally find some similarity with the electric-like sensations one might get when near orgasm. Several things can be done at that moment, and my natural tendency is to either:

• Surf on the sensation, focusing on it and sucking pleasure out of it, much like I would ride a wave of orgasmic pleasure; this is very tempting but should be avoided at least past a certain point.
  
• If the process is advanced, one thing that sometimes happens is that I tense the area again, in order to prevent it from building up more. I never actually tried to do this on purpose, but it has happened spontaneously on one occasion.
  
• it also may happen that I freak out, become anxious, and then an energetic thing of its own will start in the guts, adding energy to the whole system (which is usually very conductive at this point). This only makes things worst and can sometimes be avoided with a bit of skill (repeated intent + determination).

The way to avoid doing (1), I have found, is to notice that there is something unsettling about the kind of pleasure in question. It doesn't feel safe. Even in the beginning stages, before the process gains momentum, the feeling of fiery volatility is already there, and then it helps remembering where that feeling leads, and that will make me want to give up the orgasmic-like approach to handling these feelings.

And that is exactly the right thing to do at this point. I observe the sensations in the area that was released with an intention that reads like "I prefer the feeling of serenity to this feeling of fiery pleasure." When I incline into calmness that way, the sensations tend to slowly settle, yet leaving the area more alive and open than it was before the release. However I must maintain mindfulness, because like I said my natural tendency is to do (1-3) depending on the phase the process is in.

The corresponding gross attitude for me is to feel that I no longer desire to be euphoric. As in, I see the disadvantages in that. This attitude translates into all sorts of other things in life, such as in my attitude towards food (it is OK if I don't have super-mouth-watering food that often, if instead I am eating healthy-but-more-bland food that helps me stay healthy and more balanced).

In the context of a buddhist path, it seems to make complete sense — basically it is a skillful way of abandoning.

So far, this has worked quite well for me.

[1] Also, by the way I have described it, you can if you like imagine its complete opposite, which I have also experienced personally, where everything feels dull and stuck, the mind is prevented from moving anywhere, but neither is it comfortable where it is lying because it is hard and tense.

The elements will for some meditators not be balanced, some elements may become excessive and unbearable. Particularly hardness, heat, and pushing can become excessively strong.

If this occurs, you should pay more attention to the quality opposite the one that is in excess, and continue to develop concentration in that way.

You may find that this will balance the elements again, and it is for this reason twelve characteristics were taught in the first place. When
the elements are balanced it is easier to attain concentration.

For balancing the elements the opposites are:

Hardness and softness,

Roughness and Smoothness

Heaviness and Lightness

Flowing and Cohesion

Heat and Coldness

Supporting and Pushing.

If one member of these pairs is in excess, balance it by paying attention to its opposite. For example, if flowing is in excess pay more attention to cohesion, or if supporting is in excess pay more attention to pushing. The rest can be treated in a similar way.

My guess would be that I have too much "flowing" and I will try to focus on "cohesion".

More suggestions are welcome.

Rist thank you for your comment.

I think I already did that in my 2009-2010 retreat (12 days). At the time the kundalini energy went up from the root to the crown. After that I did get into a new stage in my practice, in fact I had to back off from practice because things were getting too intense. Intense in the same way they are now.

I basically have an ongoing background anxiety which really blows up when things get refined and silent. I don't know why, or what to do about it :-(

In five or six days, if all goes well, I should start the retreat again. I hope that I can approach the problem gently, like I sometimes do when slowly entering a very cold pool.

The condition is accompanied by an alertness that is due to anxiety. Even though I maintain myself outwardly calm and composed, and my thoughts are for the most part reasonable, the anxiety builds up by itself, simply in response to things coming loose :-(

So I really could take the dive, really just let it rip, and if it works, then great. But if it doesn't work, if it happens like it did last time, I am looking at months of severe consequences.

It is a gamble I think I would rather not do, at least as long as I think I have alternatives.