My cat has diarrhea. She has only had it a couple of days now. She is a very old cat. About 12 years old. The only problem is she is not using the cat liter box when she has this diarrhea problem. I wanted to know if there was something over the counter that I could buy for her to help make her stool hard and then what I could do to make her use the liter box. I am assuming she just does not have time to make it to the liter box. Thanks for your help.