Crunch in knee....shoulders dislocate.

I was dead lifting yesterday and on my last set (565lbs) I heard a "crunch" in my left knee. It's sore today...but no swelling. I have bad knees to begin with but I'm tired of the weakness / unstableness. I can't even do cardio (Hi/Low Sprints, running, jogging)without them aching for 3 days...any suggestions? I ALWAYS warm up on the bike for 10-15 min before back or legs.

Also, I can't seem to do anything overhead (skull crushers for example) without my shoulder wanting to pop out. Granted I've dislocated them both about 6-9 time playing rugby but they heal in a week or two and I start lifting lightly then up weights accordingly, but once I reach the level where I want to start going heavy..."Pop" and it's out...I just pop it back in and move on.

Any isolation moves to strenthen the rotator and stabilization muscles?