Cytomel and heart palpitations

I am taking Cytomel and really don't like it. Shortness of breath, itchy skin, cramping in my legs, heart palpitations, headaches, nausea and insomnia.

I am a 19yr old female athlete w/Hashimoto's. When .1synthroid did not seem to be controlling my hypothyroid symptoms (hair loss, wt gain, fatigue), my dr. tried 5mcg of Cytomel twice/day. At first I didn't notice much of a change...slowly side effects appeared. I developed rashes and itchy hands, especially after exercise...finally got heart palpitations and ended up in the hospital with anaphalactic shock (probably due to these effects combined with mono -undiagnosed at the time). I am now off of Cytomel, and dr is changing me from Synthroid to Levoxyl thinking that I might have an allergic reaction to something in the Synthroid also, as I have been breaking out in hives after exercise,since I started taking it. Has anyone else experienced these symptoms? Anyone had success with Levoxyl? VERY FRUSTRATED!!!