[theBCnut]

It sounds like the old food had a LOT of fiber in it or some other indigestable matter. That’s why so many stools. Since his stool is kind of half and half, I would not all of a sudden stop the old food, unless it is truly a problem, but I might add probiotics for a couple weeks. You may be overfeeding the new food, that can cause loose stools. Did you check its calorie count compared to what you were feeding?