What Causes Hoarseness Of Voice Post Premarin Withdrawal?

Hi I had a full hysterectomy 2005 and have been taking x2 .625 premarin tabs ea day since. My Dr sugested reducing the dose by cutting in half 6 months ago. since them my voice has changed it is husky and my singing voice keeps breaking. I want to sing professionally but my voice is all over the place. I tried in the past to reduce in this way and the same thing happened. Is this a known reaction?