My body wash, designed for hives and eczema, is just GIVING ME HIVES?!?

Currently I'm using Cetaphil Restoraderm Body Wash, the kind for atopic skin. I've probably been using this for 4 days, during the night time, and I've noticed a massive amount of hives forming around my shoulders and upper arms when I use it. The hives are small little red dots. They aren't really raised, but sort of. They itch, but barely and they go away in a matter of 10 minutes whenever I get out of the shower. I used to get hives all the time around my neck when I was younger, but they were BIG raised red harsh hives, so I'm not really used to this kind. I've been on a antihistamine for about 2 years now (xyzal), and since then I havn't gotten the hives again, but even when I take it, I STILL get the hives from the body wash. I know the body wash is causing the hives too because I didn't get them like this before I started using it. I just don't understand because I googled it and all that came up was positive results about how the body wash helped with other peoples hives and eczema... Could I be allergic to an ingredient? Thank you so much!