Minecraft gives me headaches?

Do you wear headphones? Because headphones when playing games tend to give certain people headaches.

It's probably because of motion sickness. The only way to have a game stop giving you headaches is to get use to it. Try not to have your face so close to the screen and take some breaks once you start getting headaches; the headaches will eventually stop when your head gets used to it. If you're sick, then you probably want to avoid 1st-person view games until you recover just in case it makes you even more sick.

See an eye doctor - you may need glasses.

That has happened to me many times! I like to keep a glass of ice/cold water next to me if I do get a headache. If that doesn't work, I tend to take a 5-10 minute break then resume afterwords. Or perhaps you could try to do a 'brain game' like look online for IQ tests or something? Try something that activates your brain!

Go to the settings and make the FOV higher. Its what helped me. It may look weird at first but you'll see its better.