Sinus Medication Solution

My 14yr old son has passed out several times and has had all possible tests done. MD seems to think it may be caused by a sinus infection. Could an untreated sinus infection last for months? We just found out about the infection and he has been treated for it. But he started passing out at the end of November. The infection was found late February. He passed out 3 times in November and twice in February. Has anyone ever experienced this or heard of passing out due to a sinus infection? Thanks…