I've never had anything like that happen. I'd stop buying it if I were you. If it's only Nutella and you have had all the ingredients in it, in other things without that happening to you then it might be a preservative that's in it. One of the peanut butter companies made a Nutella knockoff, so you might want to try that and see if thats what did it.
Also, it may very well be psychological. You could try a test to see. Get your husband to sneak some Nutella into something you are eating and not tell you and then see if it happens. If it doesn't, then it's all in your head. That is very possible. My husband used to say he was allergic to mushrooms and would get very sick if he ate them. His mother said he wasn't. I snuck them into the roast and not only did he not get sick, he loved them. Until he knew what they were. Now he doesn't go all overboard about them being in food, he just picks them out. The rest of us love them so I still use them but I always use the big ones that he can see to pick out, or if I fix his plate, which is what I normally do, I pick them out for him.
I don't know what he could sneak Nutella into without you knowing it was there, but there has to be something. Also, did you try the other flavor of it to see if it was the Hazelnuts that did it? If you haven't had the other ingredients in other ways than Nutella, try them separately and see if that does the same thing.
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I'm giving it another shot. We will see.
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