I Am An 80 Year Old Woman With Neuropathy Pain

I am an 80 year old woman with neuropathy pain that keeps me from walking. I have diabetes, but this pain came on suddenly and extends from my buttocks to my toes. I have never felt such pain and it keeps me from doing anything. I recently had radiation cancer treatment and this pain followed immediately after the radiation stopped. Are they related and what type of doctor should I be seeing?