Most headaches that are normal go away within a day or so but some headaches can sometimes last as long as a week or two.
If the headache doesn't go away within a couple weeks or it gets worse then you might want to go see a doctor or go to urgent care or the emergency room just to be safe.
Sometimes a headache may be something more serious especially if the headache gets worse or doesn't go away within a few weeks when taking normal headache medicine such as aspirin.
Or you constantly have a headache that comes and goes.
If the headache seems worse than usual then it could be a blood clot in your brain, a tumor or a stroke could be coming on.
Some other signs that a headache may be more serious are you notice a major change in the pattern of your headaches, you have an unusually severe headache, head pain that increases with coughing or movement, headaches that get steadily worse or you notice changes in your personality or mental function.
If so speak with a doctor or go to urgent care or the emergency room to be safe because if you do have a brain tumor which hopefully you don't then if it's caught and treated in time you'll have a better chance of survival.