What Causes Nausea And Vomiting With A Negative Pregnancy Report?

hi my name is bhoomi.my age 22 year and weight approximately 77 kg and hight 5'5 feet. i had an abortion 7th april 2011.now i feel very bad and also scared about if i can get preganant again or not? last two week i am trying to get preganant.i also feel nausea and vomiting.i also use hsg test but result is negative.pls suggest me what can i do?