Rest especially. If he's a picky eater, you won't be able to do what I do... I take all sorts of hot/strong tasting things for a cold, like raw garlic, raw onions, goldenseal and cayenne red pepper. You could try giving him an echinacea tincture.
Thank you Christa and Charles. I'm going to pick up some echinacea for him today. Hmmm.... he hasn't had a bowel movement yet today. He really hasn't eaten anything though. Only an apple this morning. He is drinking alot of fluids though.