What causes headaches? Besides being dehydrated?

Basically you get a headache when you are dehydrated, stressed, it's very noisy, things like that. I would advice you to drink a couple glasses of water, turn off the lights (be somewhere where it's dark and quiet) and try to take a nap. When you wake up, you should feel better. :)

Dehydration is basically the #1 cause for headaches. Also lots of noises can cause headaches. I suggest you go to a quiet space and take a nap.