Yucky Rash/Hives

Our poor baby beluga has a rash. We think it's probably from Burt's Bees Bubble Bath...which we've never tried before. It does have the same ingredients as the shampoo/wash but maybe in different combination or something....Everything else has been the same. I can't explain it but benadryl is supposed to help and if it doesn't in a few days the dr. said to make an appt. We'll see :( It makes him itchy and irritable. He did better today than yesterday and it looks like it might be going away.