Soreness under the shoulder may be muscle strain, frozen shoulder, cervical spondylosis and so on. You should consult a doctor in time to find out the cause of the disease. 1. Muscle strain: it is related to keeping the same posture repeatedly for a long time, strenuous exercise, high-intensity training and so on. As the shoulder muscles, soft tissues are strained in daily life, or the muscles under the shoulder are overworked, patients may be induced to have symptoms of soreness under the shoulder. 2. Frozen shoulder: due to shoulder joint strain and degeneration, it can cause inflammatory edema around the shoulder joint, leading to muscle soreness below the shoulder, and in severe cases, severe pain around the shoulder joint will occur, accompanied by symptoms of restricted activities. 3. Cervical spondylosis: most commonly seen in nerve root cervical spondylosis is caused by cervical spine degeneration, disc herniation, osteophytes and other compression of the nerve root, which will lead to one or both sides of the shoulder below the pain, and in severe cases, there will also be numbness in the arm, weakness of the symptoms. There may be other causes of lower shoulder soreness, so you should consult a doctor to clarify the specific cause and get appropriate treatment if necessary.