DS (5) has to wear knee high wool mix socks for school 
. The pairs we bought last year still fit in terms of shoe size, but over the year they have shrunk a bit and also lost all flexibility, so that they are a nightmare to get on and off. Is there anything I can do to stretch them again? I'd love not to have to buy new if possible because they are about £6 a pair!!
Or failing that, any suggestions for how best to wash them if I buy new ones so that the same thing doesn't happen again.
Thanks 