I have been having constant headaches for almost 3weeks and I have tried almost everything help
See a neurologist, he can best define a treatment for your headaches. there are so many types it's hard to get a real grasp of how debilitating some can be, and it takes medical intervention to solve the cause of many. Good luck.
Have you tried seeing a doctor?
Drink a lot of caffeine. Take an aspirin. Go to a doctor
Hope for the best, but don't take chances it may be brain tumor, get CT SCAN of you skull and verify if there is any such problem there.