I just got back from a trip to Orlando, FL (Disney) and got sick while I was there. It started very quickly with a very sore throat and I got chills and fever and fatigue then nausea/vomiting, loss of appetite, weakness/malaise. Now I feel better but have a post nasal drip as well as a bad bad cough that burns like crazy in the back of my throat every time I cough. I think this is the flu, but I'm not sure. could it be food poisoining? or norwalk virus? What causes all these symptoms?