Hi, hope things are better for your son. I've just recently come across socks with silver thread which are to reduce heat loss experienced by people with Raynards. If it's too late and you have painful, itchy chilblains, then you may want to apply an insulated tongue electrode (come with some vintage violet wand sets) this will genuinely relieve pain.
Raynards can be extremely painful due to the body tempreture being significantly colder - the right hand-hand belongs to someone with Raynards