I'm sorry to hear this and I feel your frustration because I'm going through a similar thing with my Starr. He had very bad coccidia as a kitten and has always had mushy stools. They've gotten worse lately and he sometimes can't make it to the litterbox in time so he poops on the carpet. The vet also thinks that he may have colitis.

So far I've tried California Natural Chicken & Rice, Natural Balance Venison & Green Pea, and he's now on Hills I/D which isn't working very well. He's also currently on purina fortiflora which is a probiotic and he's been on dewormers, and other meds but nothing seems to help.

I've been trying to avoid using steroids but now I'm willing to try almost anything. My oldest cat has to go to the vet for a recheck on Sat. so I'm going to ask the vet more about what I can do for Starr. I sure hope that you'll find something that will work for Miss Contessa. Good luck.