... currently 58 and very healthy otherwise, bike, swim and work out regularly. I Was on synthroid up until a year ago when my primary switched me to cytomil. My dosage was increased to 50mcg/2xday. My last blood worked showed I was hyper! My primary sent me for Nuclear med scan and everything is normal. I stopped the cytomil two weeks ago and I am currently taking nothing. My question is this... I feel like I have a heavyness in my chest. No pain, just feel like a need to take deep breaths. Is this a side effect of abrutly stopping the cytomil?