My 18 mo daughter had a 102 fever all day. After two doses of Motrin It just "broke". Her temp is 97 now and she's sweating. Will it come back?

Likely. Most fever producing illnesses in kids are viral.Their fever pattern is often one that comes and goes in cycles up/down for a minimum of a few days. It will do so if you give fever meds or not.The most I expect from tylenol or motrin is to reduce fever by 1 degree from what it would otherwise be.