Mystery Rash W/pics Help!!!

My 7 yr old son has a rash on his legs and feet that began as spots which spread and grew to slotches and spots. They don't itch, but the splotches burn. No illness so far. He tried on pants before the breakout, but the rash has spread. I don't know if an allergic reaction from material would spread over night.


Please help. Waiting for the doctor appointment is driving me crazy with worry.