The causes of shoulder and back pain and swelling may be shoulder and back muscle strain, frozen shoulder and cervical spondylosis. 1. Shoulder and back muscle strain: Because of keeping the same posture for a long time, such as working in front of the computer, driving a long distance car, etc., the muscles of the back of the shoulder are in a state of tension for a long period of time and damage occurs, which may lead to the soreness and swelling of the back of the shoulder. 2. Frozen shoulder: Inflammation of the ligaments, tendons and bursa around the shoulder joint will cause pain in the shoulder joint and inconvenience in movement, which may lead to soreness and swelling of the back of the shoulder. 3. Cervical spondylosis: Long-term strain, osteophytes, or prolapsed intervertebral discs in the cervical spine can cause nerve root compression. If the nerve root that innervates the back of the shoulder is compressed, there will be discomfort such as soreness and swelling. There may be other reasons for the soreness and swelling of the back of the shoulder, such as cholecystitis, myocardial ischemia, etc., which may also be caused by the disease, so you should go to the regular hospital in time and have the doctor give you a correct judgment based on the symptoms, signs and auxiliary examinations.