Not a blood circulation problem...

I took my son to the doctors today and I have been told to come back and see my sons normal G P because what was thought of as a blood circulation problem is not, according to the doctor today who discussed this with another doctor. Symptoms are cold hands and feet and one foot goes a strange colour after standing a while but when we tried to increase my sons exercises his foot started to swell ? This is all very strange because it looks like blood circulation problem but is not like a normal circulation problem. Might be toxins, I just don't know.