There are a number of reasons why underarm bumps are getting larger and more painful. The most common is swollen lymph nodes in the armpit, which can be caused by an infection, either systemic or local. Because the lymph nodes are an immune organ that removes germs from the body, they can stimulate an immune response to swollen lymph nodes when there is an infection. Swollen lymph nodes in the armpit can also be caused by hematologic disorders, such as leukemia. If there is a malignant tumor metastasis in the body, swollen lymph nodes in the armpit will appear when the cancer metastasizes. Therefore, once you find that the armpit bumps are getting more and more painful, you should go to the hospital for relevant examinations in time to make a clear diagnosis and then carry out symptomatic treatment. In addition to swollen lymph nodes, there are also infectious diseases, such as sebaceous cysts and subcutaneous lipomas, that can lead to bigger and bigger armpit bumps with pain.