My son has been on a strict GFCF diet for 6mths (he is 5 and a half). We have had great success with his behaviour and interlectual development in this time. I have been talking to a few people that said that after 3mths you can start re-introducing dairy into the diet - is this true and if so what would be a responsible way to do it.
My son has been on the diet since he was 3. He is currently 8 and we never go off the diet. Everyone I know that is on the GFCF has not introduced milk back in. I think since your child is doing well try adding milk and if he has a reaction then you will know that milk does not agree with him.