What Causes Tremors With Chilling Through Entire Body?

Have random shakes or tremors accompanied with a cold chill through entire body. Happens occasionally in just limbs and head/neck. Usually entire body. Happens when both stressed and not stressed. Not a heavy drinker. I am a smoker. I am currently 22, and this has been going on since I was 13 or 14. I am just curious if I should see a doctor about this, or if it is something that I don't really need to worry about.