I am hypothryoid and often get very chilled. You might want to have your TSH rechecked. Its never happened though to me because of the B-12 as far as I can tell. The trouble sleeping and heart palpitations could also be related to the thryoid issue. Have you had your thryoid antibodies tested? Sometimes if you have hashimotos thyroiditis it can go up and down abd cause some of those symptoms transiently

If you are particularly stressed your adrenals could be a bit fatigued and that can contribute to thryoid acting up and pain getting worse since the body cannot produce enough neurotransmitters to maintiain all the body functions at full speed.