I have been experiencing nausea over the last few weeks. i am 100% sure i am not pregnant, however cannot seem to shake the nausea, i experience this at least once a week?

Hard to guess: It can be hard to tell if a woman is pregnant because some of the symptoms seen in early pregnancy can also happen in non-pregnant women. A urine pregnancy test gives a reliable result if done correctly. One can test about 3 weeks after sex (when conception might have occurred), or 1 week after missing a period. One's regular doctor can evaluate any persistent or worrisome symptoms.