You have a headache for 3 days due to many reasons, as follows:
Exposure to nervous stress and anxiety .
Drinking a lot of alcohol .
You have high blood pressure
You have a cold or the flu
If the headache you are experiencing is a sudden or you have had it after a head injury or fall or as a result of Fever, stiff neck with a double vision, or difficulty speaking. ,you should contact your doctor immediately .