On 11/17, while operating eq. 2754 Loader in phase 2, EE said EE could feel the twinge in the shoulder. When EE woke up on 11/18 EE said it was more sensitive. As the day progressed on 11/18 at work, the repetitive motion of manually leveling the bucket sent sharp pains up the arm into the shoulder. EE contacted supervisor at 12 pm.