Are you sure it's your rotator cuff? I was having problems with my shoulders and the doctor diagnosed calcific tendinitis.
"Calcific tendinitis (also called calcific tendinopathy) happens when calcium builds up in the
tendons. It is most common in the shoulders. People most affected by calcific tendinitis are between 30 and 50 years old, and women are more likely to have it than men. It isn't normally a sports-related problem."
It was easily treated - I had an in-office procedure to loosen and remove most of the calcium deposit, followed up with physical therapy, and am right as rain now.