What do you do when you have banged you head on a door?

Check your name and the day/date.

Have a doctor check you out for concussion. (Did you see 'stars' / knocked out).

If you have 'projectile' vomiting, go to a medical practitioner (doctor) immediately.

If there is a head wound and bleeding, there will be a lot of blood. It looks worse than it is, because the blood vessels are very close to the scalp. However, have it cleaned and dressed. .