I posted a thread on it here a while back:
https://forums.phoenixrising.me/threads/oh-alcohol.55862/
Don't take the direction on it I did though, as my tolerance went up my binges got more and more severe (a litre of whiskey a day) and I've been in and out of detox over the last year, my driver's license is suspended, have an inflamed fatty liver, and likely have brain damage. Nowadays I no longer know if my cognitive deficits are from this condition or brain damage from alcohol abuse. Just sayin.
I used to get such relief from alcohol, but I'm a recovering drunk and I eventually had to give it up.
In the other thread you were rhetorically asking if it was a GABA thing or a dopamine thing. In my case I can say that it was both. Alcohol is complicated so it was probably even more than that. It certainly dampened my pathological immune reactivity.
You mentioned there is a time after a binge that you feel better, how long does that last? I used to feel better for 3-4 days after stopping but as my immune system came back online i'd begin to feel like shit again. The amount of cold sweating following a binge was astonishing. I'd have three layers on from head to toe and every time I'd lay down I'd sweat profusely. This would go on for days, and yet I still felt better.
Eventually I came to learn I have a babesia infection. One of the symptoms of which is drenching sweats, or night sweats. Probably called 'night sweats' because that's when people tend to lie down; something about this position would accelerate the killing. Those few days after drunks were the only time I ever got babesia sweats, and this only began to happen toward the end of my drinking, after I developed PEM, but I'd had the pathogen for decades. It's worth noting babesia can be life threatening for alcoholics. Something about drinking prevents our immune system from controlling it.
A lot of Lyme doctors are now saying there's a correlation of anxiety to babesia infection. I know this to be the case with me. I've suffered terrible anxiety in my life and drinking was my crutch for a couple decades. But the sicker I became the less tenable this grew as my behavior became more and more erratic, and I felt more and more poisoned by the stuff.
Anyway, babesia caused me anxiety, cognitive dysfunction, misery, and MCAS, and when I drank this all went away. Even my PEM went away. And then when I came off the binge my immune system would get back on top of the bug (to some extent) and my misery would return. I assume the bug took advantage of the alcohol to proliferate, and in so doing ceased its other survival strategy: inflaming my system.
Babesia is only present in the circulatory system, but this could perhaps contribute to your POTS. And I can tell you it can mess up your head really badly. It can do this through mast cell activation, and also through plugging up the capillaries in your brain. And alcoholics are more susceptible to this infection. Might be worth looking into.
I traded a hopeless alcoholic lifestyle for 1 malarone per day and I feel infinitely better. Of course it wasn't that easy but that's where I'm at now. Not cured, but pretty damn good all things considered.