sounds like rotator cuff tendonopothy of some kind or possible tears (which in most cases heal without any chemical or surgical operations). Pretty common in our sport; I've dealt with varying degrees of it in both shoulders and in a few of the rotator tendons.
rest, rest, rest is the best recipe IMO, a little ice in the first 48hrs if its truly inflamed. If it does not improve in a few days or you have trouble sleepin on the shoulder and have pain, see a doc.
take a trip to a physio, they will be able to pin point which tendon(s) are the issue and provide therapy to reduce inflammation as well as exercises and stretches to get back out there 100%.
The pec muscles and lats are a huge pull on the rotator cuff muscles, so stretching them can really help.