Hi. I believe Booger's post may be right on, regarding a pinched nerve. I Have permanent damage to the C-7 nerve root from an injury, and your symptoms are very similar to the radiculopathy I suffer from. The nerve feeds through the vertebrae and down into arms and corresponding side of chest.
Although I have this pain 24/7, it is often worse and hypersensitive after awakening. I have to be very careful as to the pillows I use, and the way I support my neck as I sleep.
Hopefully for you, it may just be the way you happened to be sleeping that night and will subside. If it persists, it may warrant a checkof your c-spine. Hope you feel better soon.
I would go see a Doctor about this feeling you have. and at least get checked out for it.
see what the Dr has to say? or what tests he wants to do.. play it safe !
for all we know it could be a pinched nerve ,or strain pulling and causing the feeling ?
If you have a good M.D. Doctor best to get checked out , at least you will know something of what it could be or is ?
good luck - the booger