Hello all! First off, pleased to meet you, as this is my first post.

Then... 
A few days ago I believe to have finally made my way out of the dark night (took months in real time, but very little after discovering MCTB ). All well and good, and especially the first few days of equanimity were very pleasant, but quickly this kind of... tension set in.

First, there's this sense of something big being about to happen, a feeling which I can only describe as "it's gonna pop". At best this feels like the evening before Christmas as a kid, but recently it has started feeling more and more like I'm watching a horror movie and waiting for the jumpscare. 

Then, there's a distinct feeling of "having my guard up". It feels very much like playing a video game while having food in the oven, like part of the mind is constantly occupied with keeping track of something. This is starting to get quite grating, especially when going to bed or doing something relaxing, as I feel like I can't properly rest. 

Now, I've read the chapter of MCTB on Equanimity several times, so it's not like I'm very clueless about what's going on, but it's causing some serious distress. I'm very jumpy especially at night, any small sound will spook me. Doing anything resembling practice makes my heart race very fast until I get scared for my health and stop. Yet despite this practice seems to more or less happen on its own, sometimes while going about my day, but also in dreams. 

I am a rather anxious person and bad with surprises/the unknown. Can someone... put me at ease a little? I know I should just "let it happen", but since I don't know what's going on (on a visceral level), it's very hard to let go. 

​​​​​​​Thanks!

​​​​​​​EDIT: I suppose I can at least have a chuckle at myself over how pissed off I am that this stage turned frustrating so quickly. Truly there is still much to learn about dukkha!

​​​​​​​EDIT2: in full disclosure I must also say that I am not entirely sure that this is not just A&P in which case how shit I felt before was just depression and the scary dark night is yet to come which would be... very unfortunate, and totally something I could wishful think myself out of understanding, I suppose 

Hey Akoko ooo, welcome and thanks for sharing your story! It is difficult to know if indeed you are in EQ, and it is best to be slightly skeptical but not too skeptical/tense. I see that you have read MCTB2 which has some excellent advice and info.

There are some really excellent posts in shargrol's compilation specifically on EQ - see here https://shargrolpostscompilation.blogspot.com/p/blog-page.html. Shargrol is a long-time DhO member and one of the people that have shared some excellent advice on this stuff over the years.

Being jumpy at night does not sound like EQ by the way, and neither does being scared for your health. But then again, this thing is different for everybody - so not wanting to dismiss of the box what is happening to you as not being EQ.

But please remember, if this is EQ and "it is about to pop" or even if this is not EQ, you are exactly where you are supposed to be. This moment, these sensations of tension, pleasantness, fear, etc. are what is happening and what is to be attended to and examined gently & openly. This is the territory and this is the practice! Keep going, you are doing well!!!

Let us know if we can help with anything - if you have specific questions, it might be good to share some more details about your practice, etc.

Thanks for the reply! I think I touched on EQ very briefly but fell to re-observation almost immediately after. No matter, I should focus on the actual sensations a bit more than the maps anyways, I think. 

Yes, the more you can drop the "this is EQ" and "this is reobservation" and so on, the clearer you will see what is actually happening; this can include thoughts about meditation, but make sure you don't follow them! Path is wiser than the one who walks it.
Nicely put. Letting go of knowing what is going on is what you are learning. You never knew in the first place, but now you see better the fear the un-knowing triggers (or you might say the fear the pretending to know was covering).

Can someone... put me at ease a little? I know I should just "let it happen", but since I don't know what's going on (on a visceral level), it's very hard to let go. 

Hi Akoko ooo, welcome to DhO.

Kaloyan already gave you good advice and pointers. Check in particular A&P - Dark Night Loop in Shargrol's posts compilation. Plenty of good stuff for there onwards. Also Daniel Ingram's posts compilation 1st Path Section, starting at Lists of symptoms por ñana diagnosis.  

You haven't described what your daily practice consists of: the vipassana - samatha mix, hours per day, months/years of practice, books read, mentor/teacher/sangha, etc. Check Shargrol's How to get the best advice in an online forum, just below the Table of Contents. 

In general, those who have stepped into EQ (already) have switched from noting to noticing, or note the endings of phenomena, or rest in the silent gaps between thoughts, or open their 'sight' (even if eyes closed) to the sides, a 180º degrees view. Other tools that were useful in DN, like relaxing physical tensions that arise with every thought, are handy too. As you have probably read in MCTB2 or elsewhere, in EQ you may revisit A&P and DN too, but you should be able to react cool to those experiences/moods/phenomena. If you push too hard, you'll probably have some A&P like stuff and later to DN. So, don't push hard. Some samatha should be experienced, either through vipassana or a separate samatha practice. Every yogi should have multiple techniques in their toolbox if they wish to attain Stream Entry.