i m 64 yrs old, female. in good health, all my blood work comes in good at my annual check ups. but for the past coule of years i ve had times where i get freezing cold and it always starts in my back spine and goes down and start shaking uncontrollably. i get a heating pad on my back until the shakes stop, this usually takes about a hour. but this always happens about 15 to 20 minutes after i finish dinner.