I've had them last up to a month before. If its not bad some excedrine helps me if not I've gone to the er before and they've helped a lot

It depends. Migraines can last weeks but everyone is different. Have you been diagnosed officially? There is a lot of medical uncertainty in your message. I'm a migraine sufferer myself, but I'm also a medical student very close to being a doctor so your question causes me anxiety. From just what you said most likely it's migraine, but there's a small chance it isn't, so it's very important you have proper diagnostics. The length of time isn't a useful part of the diagnostic algorithm though, it is too non-specific (many things present the same way). More important things are the exact symptoms you experience, your age, your family history, what causes the headaches, and what makes them better.