Why do i get so nauseous all the time. i'm not pregnant. ?

Hard to say: This is a complex symptom, that could indicate anything from an inner ear problem, to gastric reflux, to digestive issues, to a side effect to medication you're taking or some stimulant in your environment. In fact, the list goes on and on. You should have a complete evaluation to get to the bottom of this. Start with a general practitioner, who will go system by system to look for the root cause.