My 17 Year Old Son Has Been To Three Doctors

My 17 year old son has been to three doctors and is still having this problems. Headace, bad nose congeston, runny nose, vomiting, says he feels like he is burning up but is only 1 deg. above norm. teeth hurt to chew, neck pain, diarea, been going on for two weeks have been told it was some kind of school crud by one doc., gave him nothing. second doc said it was sinisitis gave antibiotics (azithromycin) and capmist for nose, zofran for vomiting, for days later no change no effect. third says he has gastroitis along with sinisinfection, changed his antibiotics to (almotripan) along with some probiotics, catmist, Zofran and lots of water. three days no change no effect his systoms are still there he is sick and I need an answer? He is tired of beening sick and I'm tired of being treated like a stupid parent.