My 27 year old son has a small lump and tenderness behind his nipple.  He has been treated for 10 days with flucloxicillin but still feels unwell.  The breast area is tender and there is slight tenderness under the armpit.  His symptoms generraly appear flu like. His doctor has said it may be a cyst which is infected.  He has now finished the antibiotics and is going back to see his GP early next week.  Do you have any advice.  Elaine
Welcome to Chat Doctor .1. The history suggests that it can be infected cyst or an abscess or infective collection under the nipple.2. If the antibiotic course has not helped - then needs further evaluation.3. An ultrasound will be best to assess the pathology - it will help in analyzing the nature of the lump, its source and its extensions. At the same time axillary tenderness also can be assessed.4. Axillary tenderness will be probably musculoskeletal pain radiating or a lymph nodal enlargement due to localized infection. 5. In this case of infective collection the treatment of choice will be - small incision and Chat Doctor.  Good luck. Hope it helps you. Wish you a good health. Anything to ask ? Do not hesitate. Thank you.