He has a headache. His headache started an hour ago. His head feels like it will explode. Of course, his head wouldn't explode. It just feels that way. The headache is in the back of his head. That is where his headaches usually are. Sometimes he has headaches on the top of his head. Sometimes he has headaches in the front of his head. Sometimes his headaches are between his eyes. Sometimes his whole head hurts. But usually the back of his head hurts. His headache started while he was reading. Reading causes headaches for him. He hates his headaches, but he loves to read. He reads for only 15 minutes. Then he stops reading. He takes a break. If he reads for 16 minutes, he'll get a headache. So he tries to take a break every 15 minutes. But sometimes he forgets to take his break. Today he forgot to take a break. Now he must wait until the headache goes away. It will take an hour or two. Then he can read again. But right now he must live with the pain.