When I was little, my mom would give me a warm sponge bath. It worked really well. I always felt WAY better after.
You use warm water, NOT cold, and only uncover what you are washing, then cover & undress/uncover another part etc.
I haven't used it with my daughter,she's only had a fever once or twice, and I've just used tylenol or motrin. I may try it next time.
You could try it early one & use tylenol if it doesn't help enough.