My son is in a school for Pervasive Developmental Disorder (PDD) kids and a lot of the kdis there are on a casein free and gluten free diet. Their parents believe it helps them. I understand that it takes some work and the whole family must buy into the changes. I also understand that if they look hard enough they can find an acceptable substitute for just about anything. I was curious as to your question about milk and put in search terms on yahoo "autism and gluten" and came up with many, many sites. Some of these list specific products, evaluate those products and some sell the products.
In looking at some of these sites I was also reminded that some professionals do not believe that the issue is an "allergy" to gluten or casein but rather a "leaky gut", inability to digest these, etc, etc.
So irrespective of the allegist's tests for allergies you might want to try these diets for while. I also understand from other parents that once the child is on the diet any amount of casein or gluten consumed has an immediate effect, similar to the effect of a child with a problem with a dye. It's immediate and dramatic.
