You most likely have an abscess. This could have started from an ingrown hair or blocked sweat duct. In any case, the treatment for an abscess is generally to cut it open and drain it. Taking antibiotics alone does not do the trick, unfortunately. The warm soaks are good, and it s possible now that it s somewhat open, it may fully drain. You do mention it s still big and painful, so the best idea is get to your doctor or urgent care, and have it a doctor properly drain it. Hope this helps.