Pain in the armpit and back may be caused by the following reasons: First, it may be caused by inflammation of the muscles and soft tissues of the armpit and back. Second, the pain may be induced by cervical spondylosis. If the lesion of the cervical spine compresses the nerve roots of the back of the shoulder or the upper limb, it may cause nerve pulling pain in the back and the armpit, which will be accompanied by the symptoms of discomfort in the cervical spine, or the pain will appear or worsen when the cervical spine moves to a certain position. Third, it may be caused by misalignment of the small joints of the thoracic vertebrae and compression of the nerve roots in the back. In addition to the pain in the axilla and the back, there will be a very obvious pressure point in the middle of the thoracic vertebrae, and it will be accompanied by the limitation of the activity function of the thoracic vertebrae.