There is no specific treatment for mono. The best thing he can do is try to relieve the symptoms using Ampicillin, amoxicillin and Acetaminophen.He also needs sufficient amount of sleep and rest so he shouldn't go to school for a while. However, most importantly he needs to see a doctor.
He should take vitamins and eat well. Get lots of sleep. Not lift anything heavy. No wrestling or physical play. He should not share food or dishes or utensils with others, and he should clean up after himself in the washroom.