A naturopathic physician will take blood (I don't remember it being a lot) and send it to the lab for a Food Panel. Basically, it runs 50 different foods that are commonly allergenic and in about two weeks, you get a bar graph with all of the foods and a quantitative result that shows how allergic your little one is to each thing. It must be interpreted by an ND, however. You can't go by what the results just say. We did this with my son and the results have been amazing! He is hardly ever sick. His ezcema cleared up. He hasn't had any fluid in his ears and sleeps like a dream!Hope your little one feels better soon.