I have a 15 week old bull/neo mastiff and he has food allergies to grains such as cornmeal, rice and things of that nature. Right now we are feeding him Wellness brand White Fish and Sweet Potato formula and he seems to like it, but he has terrible gas. It's enough that sometimes I have to leave the room, lol. Any suggestions as to what to feed him? We plan on putting him on a raw food diet after he's about a year old, we were going to start him on it after about 6 months or so, but due to a surgery he had a couple weeks back, we don't want to chance anything happening to him.