My first suspicion would be that you caught some sort of norovirus or food poisoning, since it is sudden. If it is a virus, you just have to ride it out. Noroviruses cycle pretty quickly, a few days to a week or so. But, you need to be careful not to get dehydrated, as we are more susceptible. Plus, it is highly contagious, so make sure everyone is washing their hands and covering coughs (with a tissue or the inside of your elbow- NOT your hand!!!).
If it gets real bad or persists, could be bacterial or even pouchitis, then you need antibiotics. But, give it a few days before jumping to that conclusion. You don't want antibiotics prematurely.
Jan