I'm sorry the baby is sick, and if the Vets. can't seem to find the problem, then take him off of dry kibble and start home cooking. I'm sure you will find him to be healthy, happy and free from these problems. I'm always amazed when Vets. take sick pets off of pet food to put them on "real" food till they get well, then back to pet food. Goes to show you how important "real" food actually is, and how much better they get while eating it.
Here are a few sites that can better explain what pet food is "really" made of.
The Dark Side of Recycling Closer Look At A Rendering Plant Dead Cats And Dogs Used To Make Pet Food