The causes of sudden pain in the right shoulder are commonly due to trauma to the right shoulder joint and calcific tendonitis of the right shoulder joint, as follows: First, trauma to the right shoulder joint: A direct impact or sprain to the right shoulder joint can cause severe pain symptoms in the right shoulder joint, accompanied by restricted joint movement and joint swelling. If there is a dislocation of the shoulder joint, the pain will be more intense. Taking X-ray can confirm the fracture and dislocation. Secondly, calcific tendonitis of the right shoulder joint: calcified foci form in the rotator cuff tissue and suddenly rupture to produce severe pain symptoms. An MRI will reveal the calcified foci, and most of them require arthroscopic surgery and cleaning of the calcified foci and repair of the damaged rotator cuff tissues before the pain symptoms can be completely relieved. Therefore, the cause of sudden pain in the right shoulder joint should be identified and treated as soon as possible.