I had a “frozen shoulder” not caused by surgery or any other know problem a few years back. Interestingly enough I was able to paddle a kayak at the time without it bothering my shoulder. There were many scary stories at that time about things Doctors had “tried” to help with the problem. My Dr. recommended the PT route. I was making what seemed to me to be very slow progress with the PT. I seemed to be able to get it to loosen up a little during the day but it would tighten up again at night.
The thought I had was I must be doing something that was bothering my shoulder and I started going through my day looking for what it was. The only thing I could find that even touched my shoulder was I always slept at night on that shoulder. It didn’t sound like much but I started sleeping in different positions and not in my normal position at all. It was hard the first night because I was use to sleeping on that shoulder but I worked at it. In a couple of days my shoulder started to feel better and in 2 weeks I was back to almost normal.
At one point I started to sleep ONLY on my other shoulder and it started to develop the same pain. It has been several years now and if I sleep only on that shoulder for a few nights the pain starts coming back. I can sleep on that shoulder now by changing the position just a little like leaning a little back or forward.
My question to you is: Do you always sleep in the same position on that shoulder ?
Good luck. Please report back.