Pain in the right back can be caused by the following diseases: 1. Malignant tumors occurring in the lung tissue, as the disease evolves, the tumor will involve the mural pleura and the patient will show pain. Because the mural pleural body is innervated, it is sensitive to pain and is accurately localized. Patients will also have obvious cough and sputum, or even cough with blood, and will also have loss of appetite and weight loss.2. Patients with right shoulder periarthritis are mainly related to chronic strain injury, manifesting as pain in the back of the shoulder or the back, which will also lead to aggravation of symptoms after activity. In severe cases, limb movement may be limited. After diagnosis, physiotherapy is the main treatment option to improve the condition. 3. Localized fasciitis due to muscle strain may also cause pain and significant distension.