Go see a physical therapist or other doctor that is familiar with weightlifting shoulder injuries and get a diagnosis; then plan your re-hab from there. Trust me, that's the best and quickest plan to recovery. I wish I had done this right from the beginning of my chronic left shoulder problems.
If you're stubborn like I was and don't want to see a doctor, then do some online reading about Upper Cross Syndromane and Lordosis. These two postural problems commonly lead to shoulder pain, impingement, and a host of rotator cuff and soft tissue injuries. Eric Cressey and Mike Robertson wrote a great 5 part article titled, "Neanderthal No More", which might help you with some rehab ideas.
However, if you have an injury, like a labrum tear, it's not going to get better; so go get an opinion from an expert...is my advice.