Is Rash On Body A Common Occurrence After Flu?

Hello,
My 6 year old daughter had the flu on Tuesday and Wednesday this week and went back to school yesterday. Last night she started saying her back was itchy and noticed she has a rash all over her back and it has spread to her legs and neck and a little on her face. Is this common after a flu? Please let me know any information you may have. Thanks for your time!