Neo - you might want to add eye doc and an allergy specialist to the list as well.
spent most of my teen years fighting massive migraines. Turns out they were mostly triggered by an allergic reaction to grass.
if the headaches continue, have your son keep a record of when they happen, what he was doing, what he ate, what he drank, where was he, etc.
I never found a cure for the headaches (still get them now and then), but I have learned to recognize the early warning signs and some triggers so that I can "control" them.
hoping and praying that the headache is the result of the infection and nothing else.