Nausea and lack of appetite?

For around 3-4 days now I have not been eating much at all due to the urge to vomit when I am chewing. Throughout the day, even when I do not eat I feel really nauseous and it is becoming almost unbearable. I still have not actually vomited though which is really strange considering the feelings that I have when I ingest food. Has anyone suffered anything similar, what could be wrong?