I have a similar ailment in my left shoulder blade/shoulder area. I am able to work out just fine with 100% range of motion. But, usually when I am sleeping, I'll be awakened by the pain when I'm in the process of rolling over or maybe adjusting the comforter.
While I have not been to see a doctor for examination, for various, personal reasons, I believe that it may be either a calcium deposit or bone spur. Of course, I'm not sure how either of the two would have formed or taken place.
I've been plagued with problematic knees, which I first remember when I was 14 riding on the back of my dad's motorcycle. For some reason, all of a sudden, I wasn't able to bend my knees to place my feet on the pegs. When I was 22, I had finally had enough and went to a "family practitioner" for x-rays. Naturally he couldn't see anything and simply told me that it was because I worked out. Never he mind that I told him that they didn't really inflame until usually late spring to winter time. He gave me a "feel good" temporary solution and sent me on my way. Now I'm 37 and my right knee has a constant popping, when I walk, and a cracking when I sit thing going on.
Long story short. I believe I know what you are going through. Hopefully, you will be able to go to a doctor whom will give you first rate service, medication and advice to remedy your ailment. I'll just have to live with mine for a while longer or atleast until my mind loses some of it's threshold for pain.
i have the same problem in my left shoulder =[