If another boil was going to come up after the first, when would that happen? i am still on antibiotics until wednesday. when can i stop worrying?

Depends: Really depends on the infecting organism and what you mean by a boil. In the strictest sense most common boil causing organisms will be hit pretty hard by the appropriate antibiotic and shouldn't be popping up in new locations after you have been on meds for a day or so. However, a superficial skin infection such as acne or folliculitis might not respond so well to antibiotics.