Right posterior shoulder pain can be caused by the following reasons: First, frozen shoulder, when frozen shoulder is serious, it can cause pain in the posterior part of the shoulder, which can be accompanied by limitation of shoulder joint movement, and can be limited in all directions. Second, injury to the rotator cuff. When there is an injury to the infraspinatus muscle or the lesser circular muscle of the rotator cuff, pain in the posterior part of the shoulder may occur, and an early MRI of the shoulder joint should be taken for early diagnosis and treatment. Third, myofasciitis, the pain in the posterior shoulder of myofasciitis can radiate to the right side of the shoulder, so early examination and examination should be done to rule out other diseases for diagnosis.