How can I treat rotator cuff syndrome?

Depends! It can be primarly the results of rotator cuff tendinitis secondary to overuse. It can occur in inflammatory seronegative spondyloarthritis. It can also result from impingement syndrome, which pinches the supraspinatus tendon and mechically irritates it. I inject first. If pain improves for weeks or months or longer, great. If only a day or two of benfit, x-rays and an orthopedic visit next.
Physical therapy. First,, see a sports medicine specialist, for an accurate diagnosis. That MD will most likely prescribe medication and physical therapy.
First non op. The treatment is first non operative. This consists of anti inflammatories, pt, and an injection. A concerted effort at this may be a very effective method of improving symptoms. If not, surgical intervention is indicated. The surgery itself is outpatient and fairly low risk, however the recovery requires 4-6 months.