Mysterious Hives- Advise? Help?

That sounds awful and familiar, I have changes grocery store because of what you are describing.
Is she eating anything that may contain Tree nuts??
The mysterious hives have happened to my daughter twice, one from trace amounts of peanuts and once from trace amounts of tree nuts, also quickly fading but so scary.
I am not familiar with Annie's foods, so I would also give them a call about trace .
Sorry that I can no be of help, but I think this is something we probably all have some experience with .

I'm glad your daughter got better after the benadryl. For me personally, that is one of the hardest things about dealing with the allergy, sitting there wondering what caused it and hoping everything will be fine.
To my knowledge Annie's products are safe, so it sounds to me like you are probably right about the veggies being contaminated.
I live in a VERY rural community where there is only one grocery store. They've recently put peanut bins all over their produce section (which honestly is only about 10 square feet in size), including one right by the front door to the store. I've asked them to at least move the one by the front door and although they said they would they haven't so I have to drive 1 1/2 hours round trip just to by groceries. :(

Thank you!
I went ahead and gave my daughter the left over Annie's Mac and Cheese (nervously) today and as usual, it's fine. So it has to be the veggies. Even though we do wash them before cooking, this incident tells me that is not enough. Imagine customers use their hands to scoop the peanuts from open buckets and went on to pick their fruits and vegetables.... not to even think of how the store keep them in the back. I know for sure they place oranges in the exact same buckets they used for peanuts... I guess I will be driving an hour each way now to do my shopping in other stores, how sad.

It's not just the customers but the employees handle the peanuts and then handle other produce. I NEVER buy fresh produce that doesn't have a cover on it i.e. bags of lettuce, bags of potatoes, bags of oranges, bananas, bags of baby carrots etc. There was a study that I read that peanut allergen in a grocery store can distribute minute amounts as far as 10 ft. away. I buy frozen vegetables or from my mother's garden in the summer. There's lots of frozen vegetables and fruits available. I use Green Giant frozen vegetables.