Thanks for the replies. It sounds more serious than I thought. I've been doing that 5x5 protocol with chest lately so your reasoning makes perfect sense. I would get into the second rep of a workout and the pain would just make me fail that fast. Looks like I'm gonna change things up in my workouts a bit.
5 x 5 could also be part of the problem, as i said go with moderate or higher reps whenever there are joint problems so if you want something like that but without the irritation, after taking enough of a break from it to let the pain go away, try the same exercise with 8 x 8.