Years ago, I was hyper-thyroid. Raqdioactive drink killed off the thyroid and now I use Levothyroxine. I noticed years ago when my thyroid went underactive, that when I walked, my calf muscles would get very hard, and it was very painful to walk. I'm noticing now that my calf muscles are doing the same thing. Just had a checkup and thyroid levels were okay. Can you think of any reason this might happen. I'm wondering if this could be a symptom of sugar levels fluctuating. I'm prediabetic and trying to make lifestyle changes.