I used to get the same type of thing when i was in my 20's.. at times, i thought it was heart related (heart attack more than once) but the more i fiddled with it, the more i realized it had to be muscle related. maybe you stretched the muscle or did something in your sleep to cause it to cramp up (like you can your lower back)...sometimes i get the feeling just from heartburn alone! but it's not nearly as bad as it was in my 20's.. alchohol might have been a contributor to the occasions.
