Mystery Rash

A minor crime has been committed in Allergy Town, today, and the search begins to find the culprit.  My poor angel broke out in a rash/hives, mostly on her legs, but pretty much all over.  I gave her Benadryl for the itching and she didn't appear to have any other symptoms.  The only "new guy in town" was the sweet potato pancakes, but she has had them the past couple of days.  Another change is that we switched from Zyrtec to Claritin, but that was also 4 days ago.  We didn't give her Claritin, this morning, because she complained about not liking it (which she usually doesn't do) and I had noticed that it was giving her tummy troubles.  Maybe there were just too many changes going on, today.  We'll be switching back to Zyrtec, tomorrow, and we'll see how the day goes.  I guess sweet potatoes are off the table for a while.

Update: It occurred to me, as I was getting ready for bed, that it might not have been something that she ate.  It might have been our trip to Costco!!  I have only taken her with me maybe 3 times in her whole life and I took her with me, yesterday.  I wiped down the cart, but maybe I didn't clean it well enough.  They were also cooking all kinds of foods and the smells were pretty thick.  I'm wondering if that was it, and not any of her foods, at all.  It's so tricky!

Update Part 2: OK, latest theory - cross-contamination from a pre-cooked hamburger patty. I consulted my food diary (I don't keep one every day, but I do jot things down when she develops a rash) and I had fed her that patty on both days that she showed a reaction. I'm awaiting a return phone call from the manufacturer. She has eaten this food many times before, but cross-contamination can occur at any time, I'm sure.

Update Part 3!: I got a call back from the company and the ingredients in the "spices" and "natural flavors" might have been to blame for her rash.  I may never know the true cause, but as of right now, the burger patty is off the table.