What could cause my muscle pain in my shoulders?

Pain in your shoulders can come from several places.  If you have tendinitis in your rotator cuff or rotator cuff tears, it can cause pain.  Your bicep tendon also runs into your shoulder and can cause severe pain. Nerve damage in your neck can run into your shoulder and can cause shoulder pain as well. Over use of any overhead sports can also cause tears in your labrum.  Labrum tears cause a lot of pain in the shoulder.

Aching pain in the shoulders is often due to tendonitis of the rotator cuff tendons or rotator cuff tears. Injury to these muscles usually presents over the lateral deltoid muscle. If your pain is located at the base of your neck and in your trapezius muscle this is often due to your body trying to protect the shoulder and hold it close to the body causing the trapezius to spasm.