Why do I get a rash on my legs in the winter?

Ever since I was seven, I would get a rash on my legs every winter. During the summer, the rash would fade but would eventually reappear in the winter. Although they aren't nearly as extreme as they used to be I still get them. I've been to doctors and they perscribed me hormonal creams which I truthfully don't want to use. I have no idea why I get it, and what I can do to prevent getting a rash.