Shoulder pain is discomfort that comes from the joint itself or the tissues that support it, including muscles, tendons, and the capsule that helps guide motion. Because the shoulder is built for movement, even a small change in mechanics can show up fast, especially with overhead tasks, reaching behind your back, or sleeping on one side.
In some cases, the shoulder is not the only contributor. Tension patterns in the neck and upper back can change how the shoulder blade moves, which can keep the area feeling irritated even when you are doing “all the right things.”