I did take Maggie to the doc office today. Basically, they said they did not think it was from the Bactrim..They thought it was her body's response to a virus, perhaps the cold she had a little while ago. Her body is hyperstimulated an immune response and eventually it will peter out; course if it doesn't I'll have to investigate this further. So, we'll just keep a close eye on it,, Have been avoiding the benadryl all today and yesterday gave her a very tiny dose of benadryl cream(I mean really tiny) and she hasn't had a huge breakout so the true test is when she runs around outside at her soccer game on Saturday, which had previously made the hives really come out wierd, huh? I'll tell ya never a dull moment. She also got her seasonal flu shot while we were there. For the previous poster, I don;t think you can get pseudo from hives...The hives were a respone your body makes from fighting off a virus...Seems wierd but a allergic response is one type of immune response.