I've contemplated posting my story here for a while as I don't have any answers specifically but my case may have clues as to what is going on. I've had POIS since my mid-teens as I got older it continually got worse peaking in my mid-20's. I have mainly immune/cognitive issues but do get some visible symptoms like facial bloating, skin darkening on my face, and some facial tension. My primary symptoms are vocal issues, word finding/sentence forming issues, difficulty thinking in general/cluttered thoughts, can't concentrate/enjoy anything, motor dysfunction, extreme anxiety and social anxiety, irritability, intense dopamine cravings, problems orienting my body in space, burning neuropathy in my face/head, and sinus problems (worse in my left nostril). Essentially my IQ plummets into the negatives, my entire brain becomes lizard brain, and I can't act like a human being for 2-3 days. It usually starts to taper down from 4 days out. I have during that time tried just about everything under the sun, I got mild improvement from quercetin before but that was about it. Certain supplements improved my baseline but nothing could stop the episode from happening.
About a year ago I made the entirely stupid decision to grow my hair out not knowing my hair only grows out instead of down and I got into the the world of hair loss supplements. I decided to try saw palmetto and this was the beginning of the end of my life for almost a year, in fact I am only just fully recovering now. It started with a bunch of severe digestive problems and mood disturbances (very down and angry all the time), with cognitive blunting, then one day shortly after when I was "having some fun" with someone I noticed something horrifying in addition to all of the issues. I could not get hard, I couldn't feel any affection, and I could feel almost no pleasure. After working things up for what felt like forever I was able to have a single pathetic orgasm that literally felt like nothing. As time went on I began to deteriorate further, my skin sensation all over my body began rapidly decreasing, I had intense fatigue, I could not think at all, I could feel no emotions, had no anxiety but nothing else either besides a vague feeling of doom, I became nearly housebound, my memory became practically nonexistent, and my speech issues became so severe I began to slur every time I spoke in addition to everything else. I tossed everything I could at it and very slowly as months went on made progress in little stretches, eventually I was able to actually after some profound amount of effort get things going but upon the pleasureless orgasm I noticed something I had no more POIS. I was able to orgasm again with a lot effort and again I was no longer experiencing POIS. So when I came down with this condition I lost my POIS but it was replaced with something far worse.
Fast foprward to now after rearranging my supplement stack and reintegrating D3 I was able to get back to myself again, feelings, reactive libido, sensations, emotions, pleasure, and all. But now I have another problem, upon recovery my POIS has returned and with vengaence. All of the same symptoms presenting in the same ways in the same time frames. IK will also get POIS like symptoms from excitment alone and if it gets bad enough I can have a POIS mimic episode. I don't know what to do about this situation anymore as I appear to be stuck since the only way to relieve POIS for me is to trash my system with antiandrogens. I have some rare windows of normalcy after abstaining from orgasm and high dopamine/excitment activities for a long time but it doesn't take much to break things again.
The one thing to me about this condition my case proves is that there is some sort of out of control excitory loop that occurs and it starts with dopamine but is quickly overshadowed by the rebound. I have once in my later months of PFS gotten a POIS mimic window from a dose of D3 twice that after the fact crashed me back down. To get my body to accept D3 again was quite a struggle and I don't know entirely how I did myself but doing so was crucial to getting out of PFS and getting POIS again. The D3 mimic response appears to also point to some involvement of an extremely dysregulated hormone fluctuation.
