Yesterday i slammed the upper side of my head into a door, instantly had ear pressure on that side of my head that had now turned into an earache. why?

Head trauma: You have sustained trauma to your ear and your head. I strongly recommend seeking medical attention for a physical exam to sees the extent of any injury. Ear pressure may be due to blood in the ear canal or middle ear space,

Ear: Although you should check it out, you may have hit a branch of the trigeminal nerve which could give you those symptoms. Have your ear checked soon