What Causes Dizziness And Shoulder Blade Pain After Reducing Dosage Of Thyroid Medicine?

I have very sharp pain in between my shoulders blades a little more to the left My blood pressure is normal but my heart rate is 115 Feel a little dizzy off balance I have had trouble getting my thyroid meds in line and have just lowered by dose two weeks ago I went from 5.62 to .01, was taking 175mcg and now 137mcg - could this be causing the problem??