Hello, My 4 year old son has been running a high fever for about 3 days now. The only other symptoms is head ache in the back of his head as well as the roof of his mouth hurts. He tested negative at the docs for strep . I am switching between tylenol and advil every 3-4 hours. He does not seem to be getting better. He feels fine until the medicine begins to wear off. the the fever spikes up and his head and mouth begins to hurt. I have looked into his mouth with a flaslight and there are no visible sores or redness. Any ideas would be greatly appreciated. His appetite is a little low but he is eating.