answer:Ache is kind of an unusual description. I am not trying to say you described it incorrectly, just never heard that before. Here is what I think. Hyperthyroidism, which is what you had when diagnosed, can cause heart pounding, racing, arythmias, an overall feeling of anxiety, trouble sleeping, muscle pain with quick fatigue, hair loss, dry skin, dry eyes. I am not clear whether your heart troubles started when you first started the med? Or when you started to lower the dose? That would help me understand what might be going on. And, it is just the propranonal that was reduced right? You are still taking the thyroid meds? Did he lower your dose because the tests showed you hypothyroidism now? Which also can cause muscle pain, and other symptoms.