Could these lumps be Cancer?

Last month I got a lump on my left armpit. It hurt really bad and was about the size of a marble. It hurt so bad I had to hold my arm out constantly. It started going away about a week ago but has come back along with about 7 other little lumps. Now these lumps have merged together to form a BIG lump that is about the size of a half dollar and more little lumps appeard today. Could this be cancer? If not, what could it be? Im scared.
Dawn

[CCF-RN,MSN-JS]

Dear DawnCamp, Painful lumps in the breast tend to be from a benign (non-cancerous) cause.   There could be a variety of causes for the occurrence of these lumps.   Without examining these lumps and having more information regarding associated symptoms, your health history etc. my comments would only be guesses.   Your first step should be seeing a health professional to do an examination.