I've had bad shoulder problems too. I found out that what I was doing was bringing the weights too far down when doing Military press and bench press. Now I only bring it down so that my arms are just slightly more than 90%. That has helped it alot. The sports medicine doctor told me that with all the weight I was using when you bring it past 90% you're just tearing up them rotator cuff muscles. Their are also exercises that you can do to strengthen those rotator cuff muscles. I do them and they are great.