why does my head hurt 24/7?

For as long as I can remember my head has hurt, but I don't mean like I get head aches once and a while, I mean that my head aches as if it is pounding against my skull all day. It also gets worse when I am in moving vehicles and when I get up from sitting down, and at random times during the day. I have been putting up with it for years now but I don't like it, so I was wondering if anyone could tell me why it happens and/or a way to stop it. Although... I do parkour with this problem, weird huh? Anyway, I have never does drugs or anything, but I do play video games all the time and have my entire life basically, now a days I am on my compute all the time, I don't know if that info helps at all but just in case, right?

Please help if you can, I have looked online and asked around but I can't find anything.