What can I do about an extremely swollen lip after taking antibiotics for tooth abscess?

Call the dentist. You may be developing an allergic reaction. Your doctor can advise you. Usually, the medication will be switched to a different one and taking Benadryl (diphenhydramine) may be recommended. If you have wheezing and difficulty breathing, call 911 or go straight to the er.
Call your dentist. I am assuming a professional placed you on antibiotics. You should call your dentist to explain what's going on & how best to treat\deal with it. You did not mention how long ago you were placed on antibiotics. It might take longer to work, or you might need a stronger does, need to take it more frequently, a change in the specific antibiotic, or have to be seen for drainage of an acute infection.