@tysonn hey, thank you so much for this. This is an old thread but I still get notifications because I'm glad people can share their experiences of what seems to be an un-diagnosable intersection of a bunch of different stuff. Your post especially fit my symptoms to an exact T. Down to the skin rashes and the looking healthy on the outside.
For you and anyone else who's curious, my internal tremors & palpitations & muscle twitches have largely stopped because I am now in a much more stable, stress-free environment. This isn't to say "it's all in your head", but it's worth noting; like you said, a lot of my personal stuff was a psychosomatic anxiety response to my more ongoing health issues (constipation, brain fog, etc).
That being said, I'm absolutely going to look into the AIP diet (I assume that's the Autoimmune Protocol Diet). Even though the more worrying stuff has stopped, I still have an annoying IBS-type situation that definitely makes life difficult. So thank you for the suggestion!

I hope everyone else on this thread gets some answers or at least are able to share experiences. This stuff can be really scary! Sending you all love.