How Can High Fever Along With Vomiting And Chills Be Treated?

child 4yr old girl had fevers ranging from 102.9 to as high as 105.3 in a week of being ill. had vomiting for about 36hrs. was seen by her Dr. on 2 ocassions having a strep test done that came back negative. I was instructed to give her childrens Tylenol every 4hrs and prescribed Zofran 4mg/5ml solution , 2ml every 6 hrs for nausea and vomiting. her Dr cleared her to return to headstart on Wednesday of this week and for 2 days she has told me she was freezing and in hugging she felt warm ..I took her temp and it was 102.7, I gave her a dose of Tylenol. My question is what could be wrong !