What Causes Severe Itching Along With Imbalance Of Body While On Letrazole?

Hi, I had a bi-lateral masectomy a year ago with no spread to lymph nodes and no sign of other cancer problems. My doctor has me on letrazole (after trying several other drugs). I am very unhappy taking this drug. It makes me itch terribly, and affects my balance and joints. I don't see why I need to be taking such a drug since my cancer was completely removed with no need for chemo or radium. I want to stop these but my doctor seems insistent. I do not agree. What can you advise?