sorry to say nymets224, but it probably is tendinitis...i had the same problem towards the end of this past summer. I was told to stop throwing for 4 weeks, and im now doing some rehab work pitching for my HS fall team. Still some soreness, but its gradually going away as my arm strength gets back. But you may want to get a MRI just to make sure.
To get better, during the period when you are not throwing, build up some arm strength, especially in your forearms. Wrist Curls, Wrist Strengtheners for your forearms, do some bicep curls, tricep excersises, etc. Also do your normal shoulder routine. You dont want to have the reverse problem next time you go out and throw, where your elbow is fine but your shoulder is hurting.