What causes neck and shoulder pain in thyroid patients?

Hello doctor,

This is about my mother she is 50 in age and had been diagnosed with thyroid around two years back after that she started taking medicine Thyroxine Sodium tablet 50mg, and after few months it was in control but that a year again while she was still on thyroid medicine she had started having tremors in her right hand.

After some search we found that it could be Parkinson, and we had gone to different doctors from renowned neurologist but they have prescribed the same medicine Syndopa (Levodopa) and other tablets related to Parkison, and for last few months she is under shoulder and neck pain 24 hours, and as the pain is unbearable she is forced to take pain killers. I searched and found that tremors could be a side effect of the thyroid, but not sure. I am worried that my mother's problems have not been appropriately diagnosed. Please reply.

Thank you doctor,

Now the tremor is in both hand, but on the left side, it is very less as compared to the right side, and without medicines, tremor is frequent and uncontrollable with using syncope and other Parkinson related drugs the tremor is still there, but it is less. But the main problem is that she is having pain on the backside of the neck and shoulders and not able to move her right hand in early mornings for that she is taking pain killers but what I know that pain killers have bad side effects. Could you please suggest something in this case.