I am sorry you had such a bad Charley horse from that med. I have been on Letrozole since last November. It has caused bad joint pain and a trigger thumb that I will be having surgery on. I was going to try another one but am afraid of what it may cause. The one you said caused you such pain, I had heard from someone else they did better on. I guess it is individual how people respond. I use a frankincense salve that has helped my knees som. My hands are still very stiff and painful. Best of luck to all facing these issues.