I hurt my arm back in August throwing batting practice for my son's team.

The pain is between my elbow and shoulder. Sometimes it radiates down through my elbow and other times up into the shoulder itself. Most often though it is down around the bottom of my deltoid. I have good range of motion for the most part but certain arm movements aggravate things.

Who should I see to diagnose what it is that I have done to myself. Going on almost 4 months with pain. I can't sleep on that side anymore.

Thanks.