I have been taking Levothyroxene for 6 months after having half of my thyroid removed a year ago. I have never felt worse - severe shortness of breath, poor sleep, dizziness, anxiety, slurred speech, cardiac arrhythmia, fumbled words and lots more. I went on thyroxene because my TSH levels were rising and I had a few symptoms that I thought might have been because of that. Those symptoms did not go away but I ended up with the above and many more. The horror list of serious side effects on the manufacturers web site included many of my own. So I stopped the Levothyroxene. A week later I feel like I have been born again. All of my worst symptoms have gone. I'm not concerned about my thyroid levels as my free thyroid levels were stable even though TSH was rising.
Always check the side effects of your meds first if you are experiencing weird symptoms.
Cliff in Australia