Welcome to HCM.
From the history it appears like your Ulnar Nerve
is compressed, somewhere in it's path. If you have the habit of relaxing with the back of the upper arm pressing on some object, you should avoid that. Usually after having alcohol a bit too much, if you pass out with your arms in odd position, this kind of symptoms can occur.
You have not mentioned what all investigations you have done. It would be better if you could get a CT or MRI
scan of brain and spine, done.
Wish you all the best