My left shoulder has been hurting at irregular intervals for at least four months. Over the last few weeks, it has been getting worse, to the point that it was getting unpleasant to lift my arms over my head for any reason (e.g., putting on a T-shirt). Putting a carry-on bag in the overhead compartment would have been completely out of the question.
So on Friday I went to the doctor about it. She said I have tendinitis. Until she pointed it out, I had never noticed that my shoulder has developed a clicking noise during certain motions.
Anyhow, long story short, she gave me a prescription for an NSAID, a physical therapy band and a list of stretching exercises. She also gave me a list of general stretches that don't involve the band, and it turns out that I've been doing some of them already.
So I hope to be normal again in a couple of weeks (or as close to normal as I get).