hi swimtime. i'm so sorry your son has rsd. i hope being that he is so young that he will go into remission from it soon. rsd causes all kinds of skin issues. discoloration is one issue. i have had rsd for almost five years now and have had everything from purple to red to mottled skin mainly in my original rsd site which is my right hand and wrist to my other hand and feet where my rsd has since spread too. it changes with the weather and pain levels and severity of the rsd spread. i just take it a day at a time and try to do my pt stretches at home to keep the blood circulating so that my joints don't all freeze up like my wrist has from having rsd while being casted. i hope you're son goes into remission soon and feels better. soft hugs coming your way.