Lapis is absolutely right. I have been thru this with my own son. You just have to keep eliminating things, one at a time. Everyday.
One thing I noticed with all the allergy testing that my son had done is that they never tested him for sugars. Maybe they do now? Anyway, eliminating sweets was the most important thing - diet wise - that we did for him. Sugar is an immune system nightmare. Also Vit. C and acidophilus helped us. My goal was to not put anything into his body that was not going to build him up. He ate lots of vegetables, salads, soups, organic turkey, brown rice, almond butter - things like that. I don't know about cleansing at such a young age. When my son got to age 14 or so, I put him on Hulda Clark 's parasite program which he is still on. He tried one liver cleanse and then refused to do anymore! He is doing fine now, and has room to be more free with his diet.