Hello, Thank you for asking at HCM. I carefully read your question and understand your concern. A painful lump in the armpit may have several causes but because you have already had an ultrasound you already have some evaluation of it. I understand that lumps in that area can be scary but generally those lumps that are dangerous are nontender. In your case because it is found to be a limphnode they should already be able to describe it as inflammatory limphnode (which happens in case of some reaction of the limphnode to certain microbes) or non-inflammatory one (which is not related to reaction to infection and might be more serious). What I would recommend is: 1. If you have a cat at home this might be a reactive limphnode due to cat scratches and is called cat scratch disease. It is generally self limited which means it goes away in it s own but to help heal quickly antibiotics might be used, for example a week of augmentine (if you are not allergic to penicilline) 2. If you do not have cat at home than it might be a limphnode due to reaction to other possible infection, sometimes we may not be aware of the infection that causes it. Still a trial of augmentine for a week might be done to give a chance for infection to clear if it is the case. 3. If you take antibiotics as explained above and no improvement than you will need to have a breast ultrasound (if you are under 40) or a mamograme if you are over 40 years old. 4. If all the above tests are normal than probably a biopsy of the limphnode might be needed to clarify it s nature 5. If the biopsy comes out normal than it is not a dangerous lump and you might choose to live with it or you can ask a doctor to remove it surgically for you. Hope this is helpful and answers to your question. Best regards, Dr Antoneta