Your vet is on the right tract....nearly, she is trying to tell you she is having some pain, could be a colitis type thing yes...this is very often due to diet. I'd keep trying the one vet recommended for a few more days but basically he is selling you a high priced poor quality food that has some fiber mixed in..buy a pet store food that has NO grains and buy a can of PURE pumpkin( not the pie filling) mix a teas per can in...excellent source of fiber
opus, we went to the place i work and ordered a small bag of Taste of the Wild. It is a grain free food. I feed my dogs the canine formula and they have gotten so much healthier. Hope all is well in your world. I have missed this forum!
Our old kitty, Miss Teia, uses puppy pads instead of a litter box. You might try putting pads down where kitty has been pooping. The pads are soft, unlike most litter, plus it will make clean up easier. There are also trays that hold the pad. 1st few times, smear a tiny bit of the prior poop on the pad so kitty has a smell to guide her.
Update: She is still pooping on the floor. Some days, she won't go in the litter box at all. Just the floor. Still pees in the box all the time which is great but still pooping outside the box. I am completely out of ideas!!!!