Probably of no help but:
One of my cats is prone to very loose stool. I have found two causes.
The primary is giving her snacks. Anything other than her normal food in any amount will result in loose stool. One thing that surprised me is that the quantity didn't seem to matter. A single bite of ham or meatloaf or almost anything will do it.
She prides herself on her thievery skill and will swipe food off any unguarded plate (even an occasional string bean or carrot slice). Second only to thievery skill is her begging skill. She is a master beggar, it takes some time to train household members, friends and guests to not feed her. Even then they have to be watched or they may feed her, such is her skill.
Second cause is toothpaste. Sinks must be kept clear or she will lick up any drops. For unknown reasons she loves the smell/taste of toothpaste.