Advice for AFTER you've healed-up
As someone who used to have chronic shoulder issues I can tell you whenever you do chest work you should FEEL it in your chest. If you're not, chances are you need to change your arm position. When your arms are down and out and you're bringing them up, bend your elbows slightly and make like you're hugging a big beach ball. When your dumbbells come together at the top of the move they should be directly above the mid-line of your chest, NOT in line with your shoulders. I can't tell you how long I did this wrong and how much time I had to take off from repeatedly injuring myself by doing this wrong. Learn from my mistakes and always know where you're supposed to feel a move and make sure that IS where you're feeling it. If not, you're at least wasting time. Or worse, you're doing damage. All I know is I started really paying attention and, like magic, my chest muscles got sore (for awhile) and the pain in my shoulders vanished.
Good luck.