Why do i feel nausea sometimes and i was on my period for a week and a half?

Pregnant?: The combination of abnormal bleeding and nausea can be signs of early pregnancy including an abnormal pregnancy like a tubal pregnancy or threatened miscarriage. If a pregnancy test is negative, other causes of extra hormones can cause those symptoms, like an ovarian cyst after ovulation that doesn't go away in the normal time frame. It's best to see your doctor.