A long time ago, perhaps as long as 15 years, I tore my rotator cuff. In my sleep. That's right, I went to bed just fine, and woke up the next morning in pain. I managed to ignore it for about 6 months before I nearly lost all use of my arm, and the pain could no longer be ignored.
I had surgery to fix it. Fast forward about 6 or so years. Surprise! I developed Arthritis in my shoulder joint. They tell me it's common after joint surgery. They didn't tell me that little fact before I had the surgery, however.
I learned that I must move the joint to avoid the stiffness and pain. For a long time it worked. Then abruptly it stopped working. If I sit for long periods, like when I'm knitting or crocheting, it really starts to hurt. The pain has even been disturbing my sleep. I'm a side sleeper. I start out on my right side, then move to my left side. I stay there until the pain wakes me up and I have to go back to the other side.
Lately it's been so bad, I can't even sleep on my left side. I end up laying on my back, leaning to the left a little. However, I now have some help. A few days ago, my Hubs found one of the hand weights I had purchased for P.T. after my shoulder surgery. I cleaned it up, and I've been using it to exercise my left arm. It has really been helping. I am keeping it in the bathroom, and about every other time I go in there, I use the weight to exercise my arm, and move the joint.
I hope to build the strength back up in that arm. I would be happy if it just quit hurting so much all the time. It is better already, however.