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Hi, A sprained ankle produces a good amount of swelling which should be treated with ice, pressure bandage and elevation. If this is not done the swelling will persist especially if you have been immobile for quite a long time with your computer. This can cause slow blood circulation of the limb. Are you a diabetic? If so the blood flow to the feet will be usually sluggish. Take care of the swelling and do some stretching exercises of the ankle, toes and knee. If you still feel the limb is cold then you need to consult your doctor. Good luck