@Jeanjeannie
It will get better as your body settles in and adjusts accordingly. There's a lot of confusion as @kmakm has said BC put her into menopause. The menopause is a breeze for some but difficult for others, coupled with meds that are fighting any stray cells the body seems to want to rebel. For me personally menopause was a non-event, a breeze, it's just this BC battle that turned in and lately my body is not too impressed with it all!
Take care and best wishes and hopefully you will find solace
Copy and paste from the good old google. Link from copy and paste
https://www.cancerresearchuk.org/about-cancer/cancer-in-general/treatment/cancer-drugs/drugs/letrozole-femaraLetrozole lowers the levels of the female sex hormone oestrogen in the body. ... These breast cancers are called hormone sensitive or hormone receptor positive. Letrozole can stop or slow the growth of these cancers. Letrozole only works in women who have had their menopause.Apr 2, 2019