lump underneath armpit

Hi, I am 22 years old with three small children. I have gained about 90lbs in the past 3 years. I have a lump underneath my left armpit that has been there for atleast 2 years. I did not pay any attention to it previously because I honestly just thought it was something else that happens when you are heavy. It is about the size of a kiwi; it does not cause any pain or discomfort; it has never changed in size or shape; it is soft and can move easily. If this was cancer wouldnt there be more symptoms? I have no health coverage and I have never had a primary care physician. If anyone has any answers please let me know.