Hives from juice box?

I will preface this by saying we have an appointment in 1 hour to see the Dr...I'm just trying to "sleuth" & bring all the information I can to the Dr.

Yesterday my daughter woke up with hives. We talked to the on call Dr & she had us give benadryl & they went away all day up until right before dinner. Gave more benadryl & they are still here this morning. She hasn't really had anything new to eat, no new lotions or clothes soaps, etc. At first I thought maybe it was the bath (maybe remnants of bath oils? It was a stretch but a thought), but it popped up last night without a bath. Now, the only thing I can think is that she had 2 juice boxes both days. Is this even possible to cause hives? Just thought I'd reach out & see if anyone had anything like this with their kiddo.

Thanks!