What Causes Dizziness, Fainting And Vomiting While HPT Is Negative?

hello doctor today in the morning i got dizzy and i vomiited after . I am not pregnat which i thought i was but i took a home pregnacy test and was negative . The problme is that every since i ve been little i ve been getting dizzy . I start by seeing picth black then i faint for a min then it will go away . BUT this time i didnt see picth black all i saw was my head spining alot and then i threw up . Also i have sicke cell traits . what do you think it is ? amemia?