Shoulder pain can be caused by overexertion, rotator cuff injury, frozen shoulder, cervical spondylosis and so on. 1. Overwork: If the shoulder is overworked for a long time, a large amount of lactic acid and other acidic substances will gather in the muscle, which will lead to the symptom of constant soreness. 2. Rotator cuff injury: Shoulder pain may be caused by rotator cuff injury. Rotator cuff injury refers to the tearing and rupture of the subscapularis muscle and the small round muscle in front of, above and behind the shoulder joint. Patients usually have symptoms such as localized rotator cuff edema, bleeding, pain and shoulder joint dysfunction. 3. Frozen shoulder: chronic specific inflammation of the shoulder joint capsule and its surrounding ligaments, tendons and bursa, with clinical manifestations such as shoulder pain, aches and pains, limitation of shoulder joint activities, coldness, pressure pain, muscle spasm and atrophy. 4. Cervical spondylosis: When cervical spondylosis attacks, it will compress the nerve root, resulting in radioactive pain in the muscles of the innervated area of the nerve root, which leads to the symptoms of constant shoulder pain. There are many causes of shoulder pain, and it is recommended that patients go to the hospital in time to do the relevant examinations to avoid delaying the condition and causing adverse consequences.