A lump found under the armpit during breastfeeding with symptoms of pain may be due to an enlarged axillary lymph node. This is because mastitis is prone to this complication during breastfeeding, especially in primiparous women who breastfeed in an inappropriate manner. The patient manifests breast pain, which is distending and painful, accompanied by fever, and inflammation is formed, which is prone to secondary enlargement of axillary lymph nodes, which manifests itself as localized pain, and laboratory tests may also reveal increased blood counts. In this case, timely anti-inflammatory treatment should be carried out, and it is also necessary to keep the milk emptying, and the affected side of the breast to stop breastfeeding. It may also be the formation of underarm paratits, women in childbirth and breastfeeding process will make the body’s hormone level secretion is too high, the body degeneration of the breast again development, this is the paratits, generally in the hormone level gradually reduce, paratits can gradually subside, the swelling of the armpit can gradually disappear, but if the swelling is too large or pain, you need to improve the relevant examination, if necessary, surgical excision.