LivingLifeInPeace is right. They are hunger headaches. I get them pretty much everyday cause I always wait until dinner time before I eat. It's not healthy & I don't want to sound like a hypocrite but you need to start eating breakfast, as do I, to avoid these types of headaches & live a healthier life.
Human beings are organisms that obtain energy through food. The brain is the 'control center' (if you will) and when it runs low on energy it begins to work without fuel. Thus giving you migraines or head aches.
I get nauseous or weak sometimes when I go too long without food :/ I've never gotten headaches when I'm hungry.. But I do get them when I'm tired.. I guess we're all different in our own ways :) lol I hope u can figure it out and maybe even fix the problem :D