Headache for 3 days with vomiting can be due to Migraine. Take some analgesic like Ibuprofen or Paracetamol first to decrease your headache.
Next Steps
Consult a doctor to find out the cause of headache.
Health Tips
Follow these lifestyle changes to avoid headache
1. Maintain regular sleep wake cycle, even on holiday's.
2. Don't skip meals. Take regular healthy diet with adequate fluids
3. Do not consume excess caffeine / carbohydrates / alcohol or smoke.
4. Exercise daily ( aerobics and cardiovascular)
5. Identify your headache trigger and try to avoid it.