Does he break out on his legs and sometimes his upper body?
The reason I ask is I have this condition called exercise induced hives........sometimes itchy, sometimes just hot to the touch. I also get it going from cold to hot temperatures, but mostly it was getting bad when I exercised.. I went to the doctor, she prescribed Zyrtec, which I take every day, I exercise, no rash... If I forget to take the zyrtec and go work out, I get the rash..