Why do i get migraines and headaches so often?:/?

so im 14 years old and i have mild anxiety and stuff and im always stressed out too. ive been having migraine disorders since i was 11 and i was diagnosed with chronic headache disorder and stuff but i still get them soo often even after taking excedrine. im just scared that i have a brain tumor and stuff. i dont have seziers (how ever you spell it haha) but i just have bad weird headaches. and get tingles sometime. i only get nauseated and dont throw up. i think i might have tension headaches cause those are caused from stress and anxiety. so any ideas what might be going onn? thanks!:)