Pain in the armpit near the chest is commonly caused by the following common causes: First, the pain and discomfort caused by fatigue and strain of the pectoralis major or minor muscles after strenuous activity and strain of the local shoulder joint, which usually disappears after 2-3 days of rest; second, the pain and discomfort seen in female patients during menstruation, which is usually diagnosed as cystic hyperplasia of the breast and requires an ultrasound examination for a clear diagnosis. The diagnosis is usually cystic hyperplasia. If the symptoms are severe, you need to take oral treatment of prolotherapy or breast disease; third, see herpes zoster or costochondritis, herpes zoster secondary to the virus, the infection manifests itself as pain, sharp stabbing pain, the epidermis may have red spots, the treatment is mainly anti-viral treatment, costochondritis is mainly a rib nerve dystrophy, and the symptoms appear, you need to take oral vitamin therapy.