Why do I get headaches at school?

I’ve always gotten headaches started in middle school and now I’m in college whenever I’m in school. I know it sounds crazy but it’s true. On the weekends, I’m fine. When I’m at work, with a whole bunch of preK kids, I’m fine. But as soon as I go to class, I get a headache. Could it be the lighting or something?

I’ve been to doctors about it when I was younger but nothing was ever accomplished. Now I don’t have any insurance to go back and get tests.