Try doing a lot more exercises geared towards strengthening your shoulder joints/rot cuffs. Keep an eye on your form for chest presses, especially incline. A lot of ppl put too much strain on their front delts when pressing. A slight incline is all you need to help eliminate front delt usage.

lowering the weight and concentrating on proper form could be beneficial as well. I had the same problems awhile back - one thing that has definitely helped me out is John Meadows banded over and backs. stretches out your pecs but helps with shoulder flexibility and strength. Look it up on youtube!

Cheers.