The reasons why the patient’s arm twitches and hurts are as follows: 1. Frozen shoulder: the pain of frozen shoulder is more widespread and can radiate from the neck to the shoulder, and can also manifest as pain in the lateral deltoid, lateral upper arm and axillary area, so it will manifest as a twitching pain in the upper arm, i.e. a cramp-like pain sensation. 2. Rotator cuff injury: when there is rotator cuff injury, the patient will experience pain in the shoulder joint, accompanied by 3.Neuropathic pain caused by cervical spondylosis: When a herniated cervical disc compresses the cervical nerve root, radiating pain in the upper arm can occur.