Chronic/Life-long tendinitis?

I think I got it about 5 or 6 months ago, I can't remember. I felt pain in my shoulder, but I didn't know what it was, so I just lifted through it. I went to the doctor and he said that I had tendinitis, and to stay away from certain exercises. I waited a while then went back to my normal routine, but it flared up again, I don't think I gave it enough time to heal, or I didn't ease back into my exercise or something.  Since then, the pain has eased off significantly, but I can't get past the dull ache that it bring, it seems like it won't fully heal.  I may have been doing some exercises that are bad for it(vertical chest press, pullover, pec fly, row?), and we just started the swimming unit in my P.E. class.  It doesn't hurt when I swim, but afterwords it is sore.  My trainer said that this would be good for it, but I'm not entirely sure.  I do boxing as well, and I feel no pain from it.  Could this be injuring my shoulder too?  I just do a lot and I'm not sure what it is that is causing it, and I don't want to just quit everything, but the one thing I DON'T want is for this to become a life-long injury.  Please help, thanks.

[rhaver]

I'm having the same issue with tendonitis in my elbow. It happens after I do inclined dumbbell presses. I believe it is the work of getting the weight to the press position from sitting on my thighs. Anyway, my doctor told me that I need to give it at least 3 weeks of not irritating the area with the presses. Then he told me to go light for another 3 weeks. After that, I'm supposed to stretch and do a light warm up set prior to the real sets and that it may occur again, but perhaps not.

I'm not about to spend a month and a half doing self therapy, so I've just been icing my elbow after the workout. That helps a lot with the swelling! Another option is a cortisone shot, but that isn't a permanent fix either.