When the feet were cold and all of a sudden warm with red blotches what is happening?

When your body is below the average tempreature of 37.5 degree's the body restricts blood flow to the skin capillaries allowing your body to keep in as much heat as possible when shocked with warmth soon after the thermolagatory centre in your brain tells your body that there is sufficient heat avaliable therefore increases blood flow to the surface of the skin attempting to loose heat which is why your skin turn red and blotchy so you can see the blood vessles.