I'm so sorry Chloe is ill. I use BalanceIt, but I believe it needs to be started gradually. That's what I did when I started it with Katie, but she was three years old. If you decide to use it in the future, use it gradually so that she can get used to it. See page two of this sample diet.
http://www.petdiets.com/userfiles/files/samplediet.pdf
I hope Chloe gets better quickly.