There are 4 muscles that make up the rotator cuff of the shoulder... Supraspinatus, Infraspinatus, Teres Major and Teres Minor. These muscles rotate and lift the shoulder. Putting on a shirt or bra, lifting a child, or just normal activity will hurt. The power supply nerves for these muscles comes from the neck and upper back. Typically people get injections to the shoulder but this does not solve the cause of the problem which can be coming from the neck, upper back, and shoulder joint. The cause is often a movement problem which the injection does not address.
Chiropractic adjustments to the neck and upper back as well as the shoulder along with cold laser and some exercises work wonders.