My Son 13 Yr Old Male Has Had A Fever

My son 13 yr old male has had a fever for 6 days now. In the first days was up to 104 consistently once Motrin wore off. Now last couple days at 102. Fever comes down with Motrin. Pediatrician ran tests said it was not Flu type A or B or strep throat. He is very tired, has headache when the fever is high and now last two days has heavy unproductive dry cough. He has Vasovagal Syncope and has passed out already once and two other times got dizzy but sat down in time and did not pass out. he fluctuates between being really hot and then really cold - mostly cold lately. I have been in close contact with him and do not have symptoms of anything. He is eating a little , I make sure he is drinking. Is very pale, does not really have runny nose so figure it's not a cold. If he doesn't have a cold or the flu what does he have? Any insight would be greatly appreciated.
Christina (mom)