I hate when kids get sick! What has he been eating. No one gives importance to food I swear it's one of the most important factors in this cases. Please read the China Study so you understand a little bit more, I have my own experiences. i can just advice... cut pretty much any kind of food, except raw fruits and veggies... give him lots of water and watch how he's doing in 4 or 5 days. He'll be going to the bathroom a lot and have a lot of mucus, that's normal. Try it, worse thing can happen is he'll detoxify from all the junk food we usually eat... plus he'll have lots of nutrients from fruits and veggies... Try reading something on raw vegan diet and how it relates to colds en fevers... hope this helps..
Has he been seen by an Infectious Disease doctor?