I wish that i knew the ans but i do not, but go to the dr, maybe he can help i do hope that you get better soon luck jo
I would hazard a guess the answer might be compression of a cervical disc. If you apply axial traction and the symptoms diminish you have performed a definitive test.
By now you may have found the reason, but I am having the same thing and am seeing a Physical Therapist who has prescirbed a series of gentle exercises . I have Scoliosis ( probably from birth or at least found abt age 14 ) in my upper back, also Fibromyalgia.
This just seemed to start " out of the blue " so to speak but in reality is probably from the Scoliosis and poor posture, leading to my shoulders/ back developing a forward curvature. Now, I have pain and burning on the shoulder blade itself plus down my arm and somtimes in my fingers, also vy sore under that arm. I do cross-stitch and am on the computer both requireing forward bending. At 71, I don't know how much can be accomplished and have only had 2 appts. and think with doing the exercises regularly it is beginning to let up some. I also have a habit of sleeping on that side which throws my back into forward curve but of course only makes things worse, especially if I fall asleep in that position and don't change positions often.
In past years I've had Chiropractic treatment for other back problems but decided at this age and with Osteoprosis, maybe that would be a bit too agressive a treatment.
Hope you find something that will help.