It sounds like Fifth disease. This has been going around my son's daycare for about a month now.
The following is from babycenter.com
My toddler's cheeks are suddenly bright red. What's causing this?
It could be fifth disease, also known as parvovirus B19 infection, erythema infectiosum, or "slapped cheeks disease." Fifth disease is one of the red-rash diseases common in childhood, along with scarlet fever, measles, rubella, and roseola.
Fifth disease is caused by the human parvovirus B19. Despite all these scary sounding names, it's a relatively mild illness. It shows up most often in preschool- and school-age children in the spring, and most kids recover from it with no problems.
Babies and adults don't often get fifth disease, but they can. Over half of the people in the world have had the virus and are therefore immune to it.
What are the symptoms of fifth disease?
About a week before the rash appears, your toddler may run a slight fever, feel achy all over, or appear to be coming down with a cold. When the rash shows up, your child's cheeks will be red and look as if they've been slapped.
A red rash may also appear on his trunk, hands, and feet. Sometimes the rash is itchy, but otherwise your toddler will probably feel fine while he has it.
While the rash can last for months, it usually disappears in a week to ten days. It may reappear if your toddler is very warm — from a fever or on a hot day — or if he becomes very upset. As the rash diminishes, it sometime looks lacy.
Not every child infected with the virus will get sick. About 20 percent of infected children and adults have no symptoms at all. And while adults often feel joint pain with the disease, children rarely do.
Hope this helps!