What Is The Treatment For Bumpy Rashes In The Face?

My daughter has a flesh colored bumpy rash all over her face, back, and chest. We kept giving her benadryl, but it continued to get worse and her face got so swollen you could hardly even see her eyes! Her cheeks turned red and purple from having fever in them. I now have the rash all down my back and now my son is getting it on his face. What is this?