Have sharp pain in the outside muscle in my upper arm, shoulder area. Also have sore muscle on tricepts ?? Muscle between elbow and shoulder. This happens any time I do work using my arms, like weed eating grass. The other muscles hurt when I sleep or sit in my recliner with my elbow on the arm rest. I am 79 years, and 5 mos. Have type 2 diabetes, take metformin, and 1/2 blood pressure pill a day. Otherwise, pretty good health. Curious about the muscle pain in my right arm. Was once in left arm, but not now, only right.