Food poisoning, a bacterial infection, irritable bowel syndrome, a UTI--take you pick. Nausea, vomiting and a fever are typical of "stomach flu," which is a bacterial infection. If you vomit what is in your stomach and or Don't eat much for 24+ hours, you want have much in your GI tract to eliminate. A UTI is also a type of bacterial infection. Most people don't get a fever, but any time you have an infection, your body's response can include a fever.
Serious issue are rare, but possible.
You have to decide how much pain you are in, how worried you are, and whether you want to go to the doctor or not. You can call your GP now or visit an urgent care clinic today. Your other option is to give things a couple of days to get back to normal. If any symptoms get worse or you don't feel back to normal by Monday, go see your GP.