What Causes Vomiting After Eating Chicken Pizza?

i ATE A PIZZA MADE WITH A SMALL AMOUNT OF CHICKEN THAT WOULD HAVE BEEN 2 DAYS PAST IT S USE BY DATE. i FELT ILL WITHIN AN HOUR AND BEGAN VOMITING AND FEELING VERY ILL. AFTER 8 HOURS IT JUST STOPPED AND i FELT FINE, WAS IT FOOD POISONING? i WAS PERFECTLY WELL PRIOR TO THIS.