My Husband Has Had Two Episodes Within Two Weeks Of

My husband has had two episodes within two weeks of a sharp pain in his back followed by feeling very cold with violent shaking and weakness. He is trim, 80 years old, and had a workup prior to a hernia repair in March 2015 that revealed a healthy heart and body with all blood work, chest x-ray and EKG within normal limits. He just called me on the phone from town with these symptoms (second spell of this nature as mentioned above). When talking to me on the phone his voice was very shaky and he said it was because he was so cold (it is warm out today). He was diagnosed with polyneuropathy 21 years ago and it has been slowly progressive to the point that he has been in braces for 10 years now. Thank you very much.