The answer is that you're a hypocrite for eating it in the first place if you're trying to sell us on not eating it in the first place.
Beyond that, if you hadn't eaten grains for so long, perhaps you had a reaction because your body was all like "what the hell, I don't remember these" and not "oh my god, I can't deal with these grains!!!11".
Beyond that, if you hadn't eaten grains for so long, perhaps you had a reaction because your body was all like "what the hell, I don't remember these" and not "oh my god, I can't deal with these grains!!!11".