Dd age 4 woke yesterday with a red cheek. Was warm to touch and she said it was a bit sore. I thought it was an allergic reaction to buttercups as she said she had been rubbing them on her cheek the previous day at pre-school 
She has woken this morning with the other cheek also red. No other symptoms at all. Could this be slapped cheek or allergy? We had a zoo trip planned this morning but obviously if slapped cheek we will have to cancel.
Thanks for any advice.