What could be causing severe headaches for 3 days and nights?

Common symptom. Headaches are the most common complaint that people bring to a physician. Benign causes are far more common than serious issues. 3 days of headache can be migraine, if you have a tendency to migraine, can be a viral infection, can be due to neck strain, can be due to stress. If you have vision changes, nausea and vomiting, paralysis or problems with thinking, see a doctor.