I have an 11 week old bulldog puppy. I gradually switched him from the food the breeder was giving him to a grain free food. Now his stools are soft. There is no real form to it usually, just like a pile. Do I need to just give it more time or should I switch to another brand? For his weight, I'm not even giving him all that's recommended but he is gaining weight and looks really healthy. Just concerned about the stools. Any suggestions or advice?