My 6 year old son has had a fever for 5 days. treating with ibuprofen when it goes over 101.7 . pediatrician says it is a virus. what else can do?

Maintain hydration: You must make sure that he does not get dehydrated. If it is a virus than it must run it'd course. If your son is not otherwise doing badly, ie cranky, lethargic, even when he has a fever, you could just leave it and let his body treat itself. Fever is the bodies way of activating the immune system. I would recommend you keep in touch with your pediatrician.

Good nutrition: If you have had him evaluated & the symptoms are stable; it's now just a matter of keeping him well hydrated, well fed with simple comfort items & waiting it out. If the kid isn't bothered by the fever you can let it run its course. If grumpy, treat.