I have a bad fever.

If the fever hasnt resolved by tomorrow morning, id go in. Alternate motrin(ibuprofen) 400mg with the tylenol. The best time to go to the ER is at approx 3am to 7am. slowest time. Are you having and neck stiffness/headache, nausea/diarrhea? Drink alot of fluids too like gatorade.