Shoulder pain usually comes from a few everyday causes. The most common ones are rotator cuff injuries (the muscles and tendons that keep your shoulder stable), frozen shoulder (where movement becomes stiff and painful over time), bursitis (inflammation of the small fluid-filled sacs in the joint), and general muscle strain from overuse or poor posture. Sometimes pain in the shoulder can also come from your neck or upper back — so it's not always the shoulder itself causing the problem.
