What Causes Barking Cough With Welts On Elbows And Knees?

my daughter has a barking type cough. feels good to cough she says. Her pediatrician prescribed Qvar on Friday afternoon. Sunday morning she woke with hives or welts on each elbow and her knee caps. They itch and hurt. Avarice was stopped but here we are at Tuesday and she developed more large welts in tops of feet where ankle is. Went to on call pediatrician and says she has no idea at all what it is and if she is contagious. She is using a neb to help with cough which is still present. I am to see her regular pediatrician tomorrow with hopes he has a clue....