When i get cold, i get a cold shivery numbness that goes from left side of head down to my toes .. why?

Question debatable.: I would not know about the shivery numbness specifically on the left side; but the nerves sense the temperature of the skin and send information to the brain that tells other parts of the body to produce heat to warm the skin is why you shiver. The purpose of the shivering is to activate the muscles to produce heat and warm the skin. The sensation may be the way your nerves inform your brain.