Hope you get relief soon, I feel your pain, currently have a problem with both rotator cuffs. Thinking of getting cortisone shot on Tuesday. I need to bowl in 3 weeks after taking the summer off. Physical therapy didn't help me though, but I did go bowling to see how it felt the other day and the day after, it hurt, but then it felt better than it had all summer. I wonder if I should just ignore it.
Good luck, I hope you find out exactly why it was frozen though, it seems that information might come in handy.