Dull, throbbing pain.
This might be hard to accurately describe, but I'll do my best. Sometime ago I started to get tendonitis (or it may be tendinosis), in my right arm/shoulder, most likely from playing racquet ball. Well it seems to be migrating.
Basically what seems to flare it up is static holds, like when doing squats. I can complete the set of squats and only AFTER the exercise is complete there is this deep throbbing pain, almost like its inside of the bones, in both of my shoulders and arms. Rock climbing also causes the pain to flare up, what's really crappy is it doesn't present itself until after the exercise is complete, and the degree of pain seems to depend entirely on the intensity and duration of the exercise.
The worse it's ever been was after arm wrestling someone, my entire right arm hurt so bad I was turning white and couldn't function for a few hours, it continued to throb for a few days.
Once it flares up, if I do something that requires a lot of strength in a static position it'll keep coming back for days, such as breaking loose a stuck bolt with a wrench, or unscrewing a tight lid.
Medium to heavy repetitions of lifting weights do not cause flare ups or problems, overhead press, bench press, etc do not make it worse, and sometimes even helps.
I've broken my collar bone, middle finger and thumb, this is probably more painful.