Morning sickness but definitely NOT pregnant

Kori

So for the past couple of weeks when I wake up in the morning I've been feeling really nauseous, but I don't need to go number 2, and I don't throw up. Just kind of get cold sweats and feel like I MIGHT throw up but never do. It's always only in the mornings, and there is no way that I'm pregnant because my only sexual partner is another girl. Does anyone have any idea what might be going on?