Suggest Treatment For Rash

hi,

my name is jamie, and i am 13 i am a member of st john ambulance and i have a friend of the same age of me and he has went to the local gp about a white, raised and large serface area rash. this acures when he goes out side only when it is cold it begins to devlop on his skin and spreads i thought it was thery simmulor to prikely heat but white and acurs when it is cold like i have menchand as i said about him going to the local gp they had no idear what it was and neaver did i. i told the members of my local st john ambulance but we are unknown as well and where curious to find out so my freind has asked me to find out. oh yes we are male if this helps

thanks

yours sinserley jamie trusler