I am having the exact same pain; I've had it before for a long time then for some reason it went away. Several weeks ago it came back, only a little more severe, and now I have it (much weaker on the other side. Went to the doctor, had x-rays taken, it turns out I have Bursitis. She suggested I not work out for 2 weeks to see if it made a difference, it did somewhat, but I decided to go ahead and start doing upper body anyway, 2 weeks is enough, although I'm sure that if one were to rest a month or so you would see better results I just don't want to lose my tone. I have found that taking ibuprofen on a regular basis really helps a lot, and I'm also trying to ice my shoulder after a heavy work out, although I'm rather lazy about this. I just went through 4 months of waiting for tennis elbow to clear up. I think all these pains or soreness are related and I'm thinking this will eventually go away.