If you're serious about the headache(though I can't understand why headless people like imagining they've got a right to have headaches
), it could be anything: from overworking to poor oxygen supply to your brain. I don't think there's a reason to visit a GFY doc('cause it's too fucking dangerous, so KEEP OUT!
), but it's a good way to think of the things you eat and drink and try taking walks instead of driving(if you drive, of course...Are headless people allowed to drive?
)