Have severe abcess in underarm, taken antibiotics, warm compresses just keeps getting worse. Cant put arm down its so swollen and painful. Advice?

I&D, derm, plastics. Abscesses that are not responding to more conservative measures may need to be incised and drained. A general surgeon can help address these acute issues. In the bigger picture, you may be dealing with suppurative hidradenitis. See a dermatologist for prevention measures. In more extensive cases, excision may be required often with skin grafting usually done by plastic surgeons.
Drainage? If it is an abscess, especially if antibiotics hasn't helped, it is important that the pus inside can be drained out effectively - you may want to check with your family doc to see if it needs to be lanced to release the pus.