system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What determines the location of a headache?
gpt
Pain management doctor here,

There are many, many sources and causes of headaches. The location and type of symptoms are the main things we look for in coming up with a diagnosis. For example, migraines are typically one-sided and throbbing while hemicrania headaches involve one side but are more continuous. Cervicogenic(meaning, from the neck) headaches typically involve the back of the head. Tension headaches typically feel like a band across the head. Cluster headaches involve very intense pain behind an eye. There are many other types, as well.

Going into the actual mechanism behind all of these is a huge topic and not fully understood -- but each of them has very different pathologies, prognosis, and treat treatment.