Headache

I've always wondered about headaches. I'm not sure if I've had a headache in my life before or not. It's not something I can't easily answer. It's like the common cold, we all know if someone has a cold, or what seems like a cold. They cough and wheeze and have runny noses. That's on the outside, so how is it that someone can all of a sudden say "oh yeah, I definitely have a headache right now..." you can't see a headache, and how do we know that every one's headache supposedly feels like a headache? That brain is a complicated thing, a mysterious, amazing thing, but how is that people are able to label an individual feeling so easily. What if someone got a headache, or what they figured was a headache, and it turned out it was actually brain cancer? I mean I can honestly say that I don't know if I've ever had a headache before in my life, or a migraine for that matter. What is the difference? When my head hurts for whatever reason I have no clue what it's called! All I know is that my brain hurts. Then we're told to take all these drugs to make out headaches go away. Alright, this "rant" is losing steam, but I just don't get the whole headache thing, how can a doctor (s) say that it's a headache for all different people when they have no clue what's going on in people's heads.