What Causes Dizziness And Nausea Immediately After Waking Up?

Hey, I'm a 21 year old female and in past week I keep getting episodes of being lightheaded, which leads to me being extremely dizzy, sweaty and nauseous. It usually happens too shortly after I wake up. I thought at first it was either not eating in a few hours, or lack of iron, but when I tried eating I became more nauseous, and my Iron pills didn't do anything. Do you have any advice?