Two things that come to mind would be rotator cuff exercises with 5lb dumbells and therabands.
Mr. Ellis has them shown on his site here: http://www.thecompletepitcher.com/pitching_workouts.htm
Hope that helps, if it's hurting doing the exercises don't think no pain no gain, cause it is definately not what you will want to do. Take it easy, on the exercises. An advantage to the therabands if you can get them is that you can adjust resistance to what you need, by moving farther away, or getting closer.
Hopefully you can put some of those exercises to good use.
Good luck on the bump.