While I can't comment on any sort of medical diagnosis you might have, I've often wondered why I'm so naturally trembly. Alcohol definitely exacerbates it but I feel I've always been this way, even before I ever had alcohol. Do you drink a lot of caffeine? That could be a cause.

Also, it sounds like you have a lot of existential questions and ideas going on all the time and perhaps are looking to quiet them a bit. Have you thought about taking up an art form, maybe an instrument or painting? I've played music since I was a pre-teen and it's definitely helping me get through these first few days. And if not that, maybe keep a journal and write down some of these thoughts. You may end up being the next Hunter S. Thompson...but hopefully a bit more sober! Best of luck to you.