You may not have a rotator cuff tear but it may be inflammed. That was my issue. After an MRI showing that for my shoulder, the doctor put me through a range of motion exercises to see at what point I would feel pain. Based on that she recommended PT to help develop the muscles around the shoulder joint and over time the inflammation disappeared. All of out joints work well if the muscles supporting the joint are developed enough to support full range of motion. That means keeping up those exercises once you have healed as well to prevent injury again.