It's not out of its socket -- you'd know that.
It may be subluxating though.
I dislocated my shoulder, and sprained my AC joint playing high school football. Neglected surgery, and did PT for 8 weeks instead. Ended football for me, because it would pop out pretty easily any time I put the arm in a vulnerable position (think rebounding a basketball, or reaching out to try and grab a running back, eating shit on my motocross bike). Sometimes dislocated and I had to pop it back in, but other times just a subluxation, where it would pop partially out, hurt like a mofo, pop itself back in, and just be semi-numb and sore for several days.
It's been 10yrs now since I messed it up. I got in to lifting like a year ago, so I'm in the best shape I've been in over that 10yr span, and it hurts much less and I feel more confident in it than I have before. I've subluxated it a few times lifting (once on overhead DB press, once on flat bench DB press, once on high pulley cable crosses), but it was very minor compared to what it felt like years ago when I did that. I assume that weight lifting has improved the strength of the surrounding muscles enough to keep it from popping out as far as it used to.
Maybe nerve damage from sleeping on it really weird/wrong? I had one time a couple months ago where I fell asleep in a really awkward position, and my entire arm (on the bad side) was numb when I woke up. I had some residual pain and very minor loss of feeling like you describe, for a couple days after.