An update: a lot has changed since my last post.
I've been practicing recognizing and accepting as much as possible, and I felt the burden and suffering gradually lifting or dissipating in the last day or two. I do now feel "calm and compassionate".
My meditation today was completely different to the past couple of weeks. Although it lacked excitement, and my concentration was not too strong, the previous thickness, murkiness and pain has mostly gone, and I was able to sit quite comfortably, being generally aware of my mind. I was able to catch and observe distractions much more clearly. I smiled almost continuously for the whole hour.
If I was previously at 3rd or 10th ñana, I'm fairly confident I am now moving beyond whatever it was. I feel like I am probably at Equanimity - or is it possible that I am somewhere between 3rd and 4th ñana? Or perhaps I was at 3rd ñana, and have somehow slipped backwards?
Usually the A&P stage of any given path cycle is very noticible. It's either like a big rushing ZzzzzooooOOOOMmmMMMM! Or a build up and KaBOOOM! Many people report strange visualizations leading up to, and even throughout, the A&P, which dissolves in to sparks or TV snow when it's over
What I think may have been the A&P (which I took for first samatha jhana) did not have this, nor have I ever experienced it. Rather it was more like very strong concentration, and a feeling of deep insight into the workings and flaws of my mind.
Is the physical pain solid and unchanging? Or is it "hard to pin down" and vibratory?
The pain was very solid, unchanging and strong in the back of my head and neck. Some of this remains, but much much less severe.
You mentioned having glimpses of the stage beyond where you're having the strong pain. Is that place more intense or less intense than the painful one? How do the vibrations change? Do you start getting more energized and happy, or do you go through an exhausted "giving up" phase followed by a neutral stage?
Though this has now passed, as I recall the glimpses were of a calmer, less intense, more relaxed place, quite like how I feel now. The glimpses were exhaustion followed by giving up into a calm tranquil place.
A couple more notes from the past couple of weeks: my sense of smell improved markedly. My dreams became very intense. I had one dream where I was steering an out of control car from the back seat, and the accelerator was jammed in position. I sometimes found it hard or impossible to sleep (though I've had bouts of insomnia for years).
There is now a strong feeling of being back to normal, but with broader and clearer awareness. I very much hope this is Low Equanimity. It feels a lot like it. Though if I have gone through the first 10 ñanas, the process has been quicker and less intense than what I understand is common.
Thanks again to all. Any further suggestions for how I should practice now?