rash on lower legs and arms

This morning my 7 year old child woke up with a rash on his lower legs covering the botton of his feet and his arms, I gave him some claritin and sent him to school but I'm planning to get an appointment with his doctor today. I wonder if somebody knows something, thanks

[Princessdaniella]

It could be an allergic reaction to the area he slept on, is it possible he had anything differant where he was sleeping?
You should make sure he sees a doctor when he is finished at school, better to be safe than sorry. But I am sure if he was well when he went to school and had no temperature or anything else he should be fine. It could have even been a heat rash if he had those certain parts covered in his sleep.