I am constantly having a chronic dull pain in my upper left arm for 3 days. I went to the ER and they took blood test, chest x-Ray, sonogram of my arm, and an EKG. They gave me an intravenous pain killer and a pill for muscle relaxant. All test came back normal. They think it is rheumatoid, not sure. If i sit up with my neck down, I don t feel pain, but it I raise my neck I feel the pain. What do you think it is? I am taking muscle relaxant and Percocet. It is a temporary relief.