Wet tail is just diarrhea/bacterial disease with diarrhea associated with it. It's good to be a Vet Tech. They have different remedies at PetsMart/Petco in the rodent section. There's one called Dri-Tail that those stores carry. I would isolate the infected rodent and clean out the cage the other healthy ones are in to prevent it from spreading. If it isn't too bad, the Dri-Tail should work. I hope I helped at least a little bit. Good Luck!

Becky