Alternatively, cut down a wool blanket to a smaller size; this is a useful repurposing for blankets that are nearing the end of their days. It must be one hundred percent wool, as this won't catch fire easily.  Spray the wool blanket with water, so it is a little bit misty. Pop it in the microwave or dryer for a little bit to heat it up. Wrap it around your neck or anywhere that is sore.

Summary:
Use a woolen baby's blanket.