Suggest Treatment For Fever And Vomiting In A Child

My 11 month old daughter has had a fever ranging between 100.5 - 103.8 since Saturday. She is very lethargic, keeps throwing her head back, is sleeping a lot, and will fall down on her tummy while crawling because she is so tired. She has no other symptoms. We have been alternating tylenol and motrin, but that only helps temporarily. She will eat baby food for me, but she will only drink about 2 ounces of any liquid at a time. Our pediatrician gave us an antibiotic for the beginnings of a teeny ear infection this morning. She has not been pulling at her ears at all. She has had this fever for over 48 hours now and no one seems to know why. Can you give me any suggestions? Thanks, Spencer (aka Worried Mommy )