John - Could I suggest you ask your Doc or Nurse for a general blood panel, with vitamins, minerals and thyroid included?
Vitamins and minerals can be just as dynamic as, say, our HbA1cs. For example, when my thyroid was beginning to struggle, not only did I really feel the cold (all over, not just my feet or any other body part), but my natural, un-supplemented Vitamin D levels plummeted from 80 (pretty OK) to low 21 (clinically deficient) in just a few months. I now supplement that daily, and run at 108/110, when checked.
Your cold feet may be nothing to do with vitamins or thyroid, but it's worth a check, before taking supplements you may not need.
I hope you find the answer. Being cold isn't any fun.