Re: Fifths disease
Definitely let the school know, and keep her and your other kids home from extra activities. It's pretty contagious, and most likely if one has it the others are soon to follow. (coming from a pregnant person who has no immunity and is somehow exposed during every pregnancy!)
The cheeks and flu like symptoms come first, then by the time she has the lacy rash she isn't contagious anymore, but the rash could last for a little bit.
Hi I'm Sara mommy to 3 little Mischief Makers