Hi I have been experiencing a weird thing. for about six days, i have had this burning in my left shoulder blade and armpit area. It feels like its been rubbed raw, but there is no redness or anything. the other thing that has happened is it started out on just the shoulder blade area, then it moved to under the arm pit and along the front of my should above my left breast is tender like its sore. I have been working out, but its not sore on the other side, which means its not from working out. what can that be? tonight, the burning is sending some sharp pains down my arm to my wrist.