My 12 Year Old Son Has What Looks Like A

My 12 year old son has what looks like a rash on his toes and fingers. He says it tingled yesterday but today it's just little red marks. he says that His toes itch a bit but his fingers don't. The red marks are almost as though they were from a light red marker yet some other marks actually look bumpy. I plan to make an appt with his doctor tomorrow but wondering what it may be.