i ve been nauseous and feeling lightheaded/dizzy for a few days now. these symptoms come and go, but for the past two days, i ve woken up and feel nauseous. i threw up one morning, but i didn t the next day. also, i ve been feeling dizzy and lightheaded; a few times when i m standing, i ll feel lightheaded and i almost blacked out one time. but when i sit down, i feel completely fine.