DS passed an IOFC and ate the allergen at home a very short time and then had a more potent form of the allergen and failed at home (dr approved to do that at home) and it was as though that turned on a switch in him. He reacted to every form of the allergen and smaller and smaller amounts and I couldn't keep it in his diet. The allergist has a very hard time to accept this and has since skin tested him and seen a big positive result to that same food that had a neg skin test and which DS at in front of him in the challenge. He seems to have the belief that you can't have the allergy come back that quickly. It really did seem that the time I gave him the more potent form of the allergen (not that much more potent than what he ate in the challenge) flipped some switch in him to make him even more sensitive than he was before the challenge.
Allergist wants to skin test again for this (and other foods) soon. I will go along with it but I know DS will test positive. He is allergic to that food now.
This same allergist doesn't believe you can have contact ingestion ana like DS has had and insisted DS must have eaten something and lied to me. DS would not do that. Even years ago when much younger he remembered ana well and didn't want it again. He has never once tried to sneak food. He knows I'll give him whatever he wants and make up for anything he misses. So, it does seem there are set beliefs about things like this. I agree with bandboosmom that allergists do have to deal with a bunch of patients who think all sorts of untrue things, people who have had 'ana' to placebo during challenges, and much more. Dealing with that all day would make me sceptical, too.