Dancer would get vaginitis once in a while. My Vet said sometimes with girls, it's just the way their anatomy is laid out, so to speak. :lol Sometimes Dancer would pee and a bit would dribble into her vigina folds and if she didn't clean herself up, she would get red and swollen. She had her very own tube of Vetalog and I would treat her for a faw days. She never had a UTI that I know of as a result though. UTI can be very painful.
Hope Ady Bea is feeling better quickly. As for more water, you can try soaking her kibble.