D.B.
May I ask if you've noticed anything else like her cheeks being warm & red, almost like they'd been slapped? The reason I ask is there is a viral condition called Fifths Disease and it worsens in the sun. Usually a rash appears where sunlight touches the skin and the face looks red, especially on the cheeks. My kids have had it in the past & I never kept them inside because they played well and it didn't seem to bother them at all, it just looked like it should, know what I mean?
You can look up Fifths Disease online & see if that's what you're seeing.