I get a headache when I concentrate for a long period of time?

I get headaches when I have to read something complex or long,memorize anything ,talk to more than one person or group of people ,try to study , even when to talk with someone in important issue.
when I know someone is going to tell me something that is important that I remember, I get an uncomfortable headache.
My biggest problem in exam period , It’s torture to study for days and try to concentrate and memorize things and on exam day it’s painful to recall things.
Medications: None