My son just turned four. What the Infectious Disease will do (better do) is have a sinus endoscopy for culture and sensitivity. This will grow whatever bacteria is in your sons head and try to kill it with various forms of antibiotics (to see if he's resistant). My son finally had that done. Even though he has three vacinations, he had HIB and staph. Don't be afraid to go to the doctors that have been trained to think out of the box. I've been telling 25 doctors that my son is sick 18 told me that it was just autism. It will be ok. Answers are a good thing.