We just went through this a few weeks ago with a 104 fever. My friend is a pediatric ER nurse and she advised me to treat the fever for 24 hours before going in as long as she's wetting diapers as usual.
Strip her to just a diaper, give both Motrin and Tylenol you can give them at the same time, and keep her hydrated with Pedialyte. Forget water and milk. She said push the Pedialyte. If the fever doesn't come down with the meds, if she's not wetting diapers, or if she's still acting lethargic or in pain even after the fever goes down, then take her in. Of course if you feel uncomfortable waiting, then take her. Hope she feels better soon!