I've had recent shoulder pain and this week I went to the Chiropractor on Tuesday, he said shoulder issues are common, and
often a muscle thing.  He explained there are 4 muscle groups and often one will be inflamed and pull on the rest.  He gave
me a deep massage on the muscle under my armpit, hurt quite a bit, and he said to ice it.
Now today, Friday, I went back and that muscle was much better and relaxed, did not hurt a bit when he worked
it.  I will keep icing it for a while.
So, your shoulder issues may be muscle related and not in the joint, good thing.  So check things out before going
to a regular Doctor, they do not have as much knowledge of this type.