Thank you for writing to us.
With the symptoms that you are mentioning i.e." intermittent cold chills
on my left thigh and lower leg leg (no pain), this is sometimes accompioned with upper left arms numbness/neck and left shoulder pain" with your history of GAD this all goes in favor of the diagnosis of GAD and panic attacks.
The great thing is that all your tests have been normal.
The chills in the legs that concern you could very well be due to panic attacks or anxiety
and these chills happen due to narrowing of blood vessels in the legs and hands. This narrowing of blood vessels is due to increased amount of adrenaline
in your body as a result of the increased anxiety that you are having.
So this is nothing serious or anything to worry about
You should discuss these symptoms with your psychiatrist
next time you visit him/her.