Diana, it might be that the clinic is giving you a bit of thyroid hormone to help you lose weight (not a good idea, but it doesn’t keep people from doing it) and this is why your thyroid tests overactive. So, before you start taking treatment for an overactive thyroid, first stop your diet stuff for a month and have your blood retested (or at least discuss this option with your doctor). Your aching muscles just might get better too. Good luck.