Hi,
I too am almost 2 years out and still have pain and tightness in my left arm. Had a radical mastectomy with 19 lymph nodes removed on June 2, 2006. My surgeon told me I would have the discomfort and some numbness, this is natural from the surgery and nerves affected.
Hope this helps ease your concerns. Have never heard of the cord, but in a way it feels like there is a cord inside when I use that arm to reach for something.
My Prayers are with you.
Bev