Hi sanal ;
Welcome to HealthcareMagic
Continuous headache for 5 days with nausea/vomiting
can be a migraine
.Also since you have missed periods and if you are sexually active then you should get a urine pregnancy
test done at home preferably with first morning urine sample to rule out pregnancy.If the pregnancy is negative then you need to consult a doctor to investigate the cause of your headache.