Strange Skin Issues

I'm a 17 year old male and I have in the past 3 years had big problems with skin specifically on my forehead. I have these small pimple like bumps, at least one is usually present at all times, but whenever one of these bumps get irritated or when I lay my head down at school and my forehead heats up (BTW this doesn't happen at home when I lie my head down) these bumps will swell up as if it is a hive or like I just bumped my head on a metal bar. And actually some people have mistaken the "bumps" for impact bumps if you know what I mean. And I believe I have Dermatology where my skin takes the shape of something that scratches me and swells up in that area. Any help is greatly appreciated.