Estrogen is especially bone protective, so as we age we start to have issues with bones because that estrogen (and possibly progesterone) protect our bones. The AI drugs given for breast cancer eliminate not only the diminished estrogen one might have after menopause but ALL the estrogen essentially. That's what causes the bone pain, the actual degeneration of bone due to the drugs. For people who may also tend toward losing bone mass......it can be especially hard.
I have bones of steal and no osteoporosis in my family but I even had bone pain in my wrists, hips and jaw............so..........(I was unable to take the AI's due to more severe side effects).........but did a lot of research and unfortunately bone pain and loss is a pretty common side effect of the AI's.
Hugs all..............