What Causes Dizziness, Hot Flashes And Chilling?

I am experiencing odd things. I call them "episodes" It usually begins with a dizzy, light headed feeling, as if im going to pass out. this can accur any time, sitting, standing, laying down. it is accompanied by hot flash and sweaty under arms, then cold chills. Then it feels as if my leg and left arm muscles tense up and ache and sometimes shooting pains. then a "dizzy" head ache with pain in temple occurs. this has happened numerous times in last week. I do have constant aching in legs and they jerk uncontrolably. Any ideas on what could be causing this.