This man did not realize that he had a nail on his head
Headaches are not something doctors should underestimate. There are hundreds of factors that might result in a migraine or a headache, so they have to work through all the possibilities to reach a conclusion and treat the right cause. And sometimes, they get an unexpectedly easy case like this.
This man spent three days with a nail in his head without even noticing it. He would not have gone to the emergency room if it were not for the constant headache. It was clear what the problem was after a CT scan; he had a large nail stuck in his skull.