I've spent many hours researching on line about migraines and causes, there's an ingredient in diet drinks that can be a trigger, exercise, sleep, lack of, too much, chocolate, alcohol, ice cream, dairy products, lots of stuff. And it's supposedly more common in women than men, and also hereditary.
Mine are the same, stabbing pain behind one eye and one side of my head. I can go months without any then a few in a short space of time, horrible, horrible things!