One of the reasons why you may be experiencing pain in the shoulder could be micro tears in the tendon which causes it to rupture with overuse and repetitive overhead arm motions. Rotator Cuff Syndrome is another reason why someone may feel pain in the shoulders. This pain is usually due to aging. The rotator cuff muscles are a group of muscle and tendons that allow the shoulder to have circular motion. Other causes of shoulder pain include a shoulder dislocation which occurs when there is an injury to the joint between the humerus and scapula. Arthritis, bursitis, and tendonitis also occur.