Other possible reasons...
I don't suffer from headaches to any degree nor indeed migraines but recently was told by a CAA doctor in relation to a friend who was undergoing a Class 2 medical that she wouldn't be likely to be passed as she had a full blown migraine the day of her med exam.
I actually have a rheumatic disorder that cites migraines as a possible symptom - in our case it can be related to tightened/spasmed 'trigger points' - muscle knots that can crop up in the neck with some people - these can then provoke responses within the circulatory system in the scalp arteries which can further evolve into migraines if not treated. The quickest way of preventing these and to my knowledge the med is okay for a medical is to take ibuprofen - perhaps someone else can clarify on whether this is indeed an acceptable med?
TR