The full name for this injury is Rotator Cuff Tendonitis. Most effective way to tell whether you have it is with an MRI. However, realizing that we do not diagnose or treat, here are symptoms from The Merck Manual:

"Shoulder pain is the main symptom 'of rotator cuff injury.] Initially, the pain occurs only during activities that require lifting the arm over the head and forcibly bringing it forward. Later, pain can occur even when the arm is moved forward to shake hands. Usually, pushing object away is painful, but pulling them in toward the body is not. The involved shoulder may be particularly painful at night, disrupting the person's sleep.

"The diagnosis of rotator cuff injury is made when specific movement, especially raising the arm above the shoulder, cause pain and soreness. Magnetic resonance imaging (MRI) is the best diagnostic tool for this condition."

Medical science has shown that taken immediately after all injuries, rotator cuff or not, bromelain, an extract of pineapples, taken for seven days (only) has shown to be helpful.

Note that we do not treat, which is only for physicians. We can say however, that plain old aspirin is the standard for pain relief. Being a drug it can cause stomach upset and over time, even an ulcer. One must determine whether or not one is stomach-sensitive (a tummy ache for example.)

Aspirin is sold in modified form (ibuprofen, naproxin, Cox 2 Inhibitors--Celebrex, Vioxx, etc.,) to raise the cost and the profit to the drug companies. Our research shows it to be superior to all its knockoffs.
In summary, whether or not you follow the above, an MRI is the gold standard for diagnosis.

Rotator Cuff Injury - Symptoms of Rotator Cuff Injury Bibliography

The Merck Manual