Is it allergy or intolerance? If an allergy it can be treated.
What types of things have you tried? We basically follow a GFCF diet at home due to fibromyalgia and ASDs in our family. We got a mill to make our own rice flour. We also use masa. Milk wise, we use rice milk and soy milk. We have come up with recipes for cookies, pancakes, spaghetti sauce, chili, banana bread, etc. We also do tacos with corn tortillas and sometimes have 'beanie tacos' (that my kids really like) where we put refried beans, onions, and sauce on the corn tortillas. Rice Chex and Honey Nut Chex work well for cereals. Does any of that sound like it would work for your family?