So, having gone over my MRI results now with one doctor and two physical therapists, I now understand that while I do have a small rotator cuff tear, it's not really the problem. The problem is the inflammation that my doctor talked about, more properly known as "adhesive capsulitis" or, colloquially, "frozen shoulder". Which might be the result of the rotator cuff tear, or the cause of the rotator cuff tear.
One of the things that I've found funny is that both of the physical therapists I've seen have gone out of their way to tell me how awesome it is that I've started treatment this early. Having read this article
, I now understand why: by getting a cortisone shot and starting physical therapy early, I might have cut my recovery time down to months instead of years.
I'm trying very hard to look on the bright side of all of this. I think I'm mostly succeeding.