Breast and armpit pain is associated with breast enlargement, mastitis, and breast tumors. The most common factor for breast and armpit pain is mastopexy. Mastopexy can cause significant lumps in the chest and appear as cyclical pain, and in the premenstrual period hormone levels increase, and edema of the lobules and alveoli of the breast causes pain at the site of the lump, which is dominated by cyclical pain. Consider mastitis caused by nipple rupture, Staphylococcus aureus invade the breast along the ducts, local inflammation causes axillary lymph node enlargement, resulting in chest and axillary pain, if the local pain is more serious, you can go to the hospital for mammography ultrasound examination, breast cancer is easy to appear single or multiple lumps in the early stage, and does not cause pain, when the malignant lumps grow faster, causing axillary lymph node enlargement which leads to local pain.