Hi! I was on Letrozole for a year and a half and experienced really bad back pain, and stiffness in my hands and ankles. MRI on my back ruled out further cancer or anything else causing the pain. My oncologist suggested the same as for you — a two week holiday from Letrozole before trying Exemestane. I had the exact same reaction and was terrified to try something new. She assured me I could go back on Letrozole if I didn’t like the side effects of Exemestane, or even switch to Tamoxifen. I gave it a try, and low and behold, everything that bothered me improved and I didn’t suffer anything new that was bothersome. Still get some back pain from time to time, but not to the extent that I did previously. If you have the option to go back on Letrozole, it might be worth a shot, trying the Exemestane. Best of luck with whatever you choose to do!