Cable & Java both had very soft stools when they came to me. the vet told me for Cable, who was only about 8 weeks, that was normal. Java's was not - got even looser, until it was almost watery [by then we were at the vet's] - she had a bacterial overgrowth. after 2 rounds of antibiotics, she was still having problems, so i got her some bene bac, & that solved the problem. so if there's nothing else wrong with the kitty, you might try that.