It took me YEARS to figure out my problem. Ever since I was a little kid I have one shoulder that is very dropped compared to the other. The ligaments are really loose and I can pop it up and down, the other one is normal. It was a problem with my riding and my posture and I'd never had an injury of any sort.

One night I was tossing and turning and trying to go to sleep. It twigged in my brain that my pillow didn't feel *right*. I rolled to the other side. Pillow felt lower. Rolled again.. pillow higher. Lightbulb moment. I almost always sleep on my left and curl my shoulder under me. I think that laying that way for long periods has stretched my shoulder ligaments. At least that's my theory:)

Of course I got dumped off a horse last year and landed with my arm up on the other side so now I'm more even, but droopy on both sides!