Being thrown suddenly into menopause does take time to adjust. I didn't feel myself for around 2years during peri-menopause. It got better.
I was very worried when starting letrozole it would be like that again. It felt no different.
Mental recovery from breast cancer isn't easy. I got really depressed from chemo and the length of time to get my energy back and brain working on all cylinders has taken 12months.
I did have really stiff ankles feet and wrists. That has definetly improved over months and I just have some morning ankle stiffness now. Exercise really helped. It lifts the mood. Improves brain finctioning and loosens up those joints. I only have issues now if sitting around too much (as well as my arthritic back then seizing )
So ...it could be a combo of things. But worth discussing with your onco. Kath x