Why am do i keep getting chills?

ok for the past few years i get chills every so offten. it started when i got sick with a cold and has stayed with me. it dosent happen to me when i get cold, altho when i feel cold it can cause me to have one. usualy i tense up my head twitches and my arms kinda flail a abit. i just want to know what might be causeing this...its been happening for the past 3 years and im worryed that it might be from some sort of defficancy, psycological problem, or something else...