Fifth's is one of many childhood rashes, go see your pediatrician, it could represent something your daughter could require an antibiotic for.
My daughter had really red cheeks, then the next day she broke out in a rash all over her body. She was also exhibiting cold symptoms. She had Fifth's disease. It's pretty much harmless and not that big of a deal, I just had to let it run it's course. It started with really red hot cheeks. I took her into the ped.