And, it's for sure something in the food? Could it be something as mundane as grass? My friend's chihuahua was allergic to grass! She indoor litter trained him and he was fine after that. But, he was little, too. I know dogs that have allergies respond really well when switched to the raw diet, but, people are understandably nervous about that switch, but, it is an option. And, are you involved with any boxer chat forums? Maybe someone out there has a similar situation? Couldn't hurt to join a couple and post pictures along with questions....