Helooo Doctor ..I Am Unmarried 26 Yr Old Girl ,have

Helooo doctor ..I am unmarried 26 yr old girl ,have a major problem of mensuration ..it always occur after a gap of 1-2 months..my one of doctor suggest me to take 20 tablets of ovanac plus for 20 days..but I am facing problem during these 20 days..like somewhere my headache is there..feel like a vomit..tiredness.why all these.. Kindly do the needful