Question About Food Obsession

My son just went to a birthday party where we let him have a piece of cake, but gave it along with AFP Peptizde enzyme. He longer shows an intolerance for wheat or eggs after a year on the diet and moderate for milk. He kept going back for more even after I told him not to. He went 3 times and got a piece, which I took from him, and we left when I saw him licking the icing on the cake! He acts similar to this when he has Sprite. He gets very hyper with that, but the cake made him seem like an addict. We limit both of these, but I was wondering if any one thought these cravings might be an intolerance of something in it.