What Causes Red Hard Sores On Toes During Winters?

I get red sores on my toes in the winter, usually when they have been cold for along time. This year, I have the red spots, but they are extremely sore and are kinda hard like a callous. Also, my toes turn red and swell some. I have had these now for almost a month without getting better. Usually I can get my feet warm by soaking them and they go away