Thank you for your question. There can be multiple causes of a lump affecting the armpit. The common causes would be an ingrown hair, infection of a hair follicle, cysts or lipomas. The more worrying causes like an enlarged lymph node due to breast cancer must also be excluded.
It is most important for you to see a doctor to ascertain the cause of your lump.
Most of these lumps can be easily treated with antibiotics or simple surgery to remove the lump, depending on the cause. I would encourage you to seek help from a doctor or dermatologist as soon as possible, so they can check you over and you no longer have to worry alone.
Hope this is helpful!
Best regards
Dr Stephanie Ho, Dermatologist
