The cat with loose poops?

Oh my yes! The wormer can most certainly cause diarrhea. It did for my cat. Two of them will make it worse. It took my cat about a week to get back to normal. I'd wait on that other food for a few more days. BUT what my vet told me to do was to get a can of plain canned pumpkin. Give kitty about a teaspoon of it a day - it adds fiber and they really like it. It worked really well for my cat and it inexpensive.