Hello dear Understand your concern Following are the causes of small painful lump on left breast: breast abscess, firbroadenoma cyst, breast cancer. I advice you to consult the experience surgeon and get examined properly for better treatment. USG guided fine needle aspiration biopsy helpful in diagnosis. But best is exclusion biopsy to rule out above causes. Radio logical finding should be correlated with pathology and clinical feature. Breast abscess require antibiotic, application of warp pad. If not responds then aspiration. Fibroadenoma treatment will depend on size of lump and severity. Cancer require excision followed by chemotherapy and radiotherapy. Hope this may help you Contact HCM for further health query. Best regards Dr. Sagar