We also had a problem with two of our six cats intermittenly having bouts with soft stool. We took the cats to the vet along with a stool sample and at first they gave us some medicine to mash up and give them with a syringe. The medicine was flagyl. I'm no vet and do not profess to know more than one but I do know what flagyl is and what it is used for. It is used for very small parasites and this is not what the problem was with either of the cats in question. Well.......that didn't work so back to the vet we go. This time I requested them to do some testing to try and find the parasites that they had been treating for. NO parasites to be found, which I don't think they had any to begin with but giving them the benefit of the doubt and *assuming* that they DID have some before the medication I asked WHY they still had loose stool. They asked if we had been giving them any dairy products or had we changed food or perhaps gave them water from a different water system than they had been getting. NO was the answer to both questions. They were at a loss as to what could be causing the diarrhea. Well.....to make an already *long-story-short* I started looking online and found that sometimes the filler in the cat food that you may be feeding will not agree with some cats systems. So.......the search began to try to find something without any (if possible) filler's such as corn, rice, and other grain fillers. We found one that had NO GRAIN what-so-ever in it and decided to try to switch our cats over to it. Anyone that has done this *switching-over* brands of cat food before knows that this is a gradual switch and *hopefully* the cats will like the new food. Well, in our case, the switch was a successful one and all six of the cats really seemed to like the new food. Since the switch there has been NO loose stool or diarrhea in any of the litter boxes. I'm not saying that this is what might fix your problem but it sure is worth a try. The food we switched to is Innova-EVO and if you can find it I believe that it is one of the best foods available for cats.