The lymph nodes are part of the body’s immune system and contain many immune cells, such as white blood cells and macrophages. When the body suffers a heterogenous attack, such as a bacterial infection or viral infection, swollen lymph nodes will appear. If necessary, antibiotics can be used for treatment. In most cases, the swelling and pain can gradually subside with the end of the breastfeeding period, but if there is no obvious relief, surgical removal is feasible. Thirdly, there are also some rare diseases, such as autoimmune diseases and hematologic diseases. If the lump persists and is painful, you need to go to the hospital promptly to clarify the cause.