Also try lean against the bumdbell rack with you back parallel to the floor, hold a 20-25 lb weight in one hand while hold on to the rack with the other(stabilization), let your arm hang towards the floor completely relaxed, swing the weight in small circles like a pendulum, your arms should not be twisting at all, if your shoulder is relaxed you will feel the pressure pull your shoulder joint apart just a hair. Swing each side for 15-20 seconds a couple of times. Helps to take some stress of the joint and reduce the pain.