I have a frozen shoulder. This is a recurrence of a condition I had several years ago. I know that it sounds like some kind of cut of meat for the table, but it is actually a problem where you have a lot of pain in your shoulder and arm, and you lose a lot of your range of motion. It is also called an Encapsulated Shoulder.
The last time I had this, a month or two of physical therapy, along with nightly exercises, eventually made it go away. So, I guess I will be repeating that experience. There is also a possibility that a shot of cortisone would relieve the problem, by my orthopedic surgeon and I have agreed to try the therapy first. I always lean to the side of no drugs if I can.
This does not seem to be a structural problem, or something you catch. It has something to do with inflammation. It is as if your shoulder just gives up and becomes lazy. Moving your arm beyond the limited range of motion causes substantial pain, and moving within the limited range of motion, but moving too rapidly can cause the pain as well.
Evidently, moving to a warmer climate will not thaw out a frozen shoulder.
BB