Oh Huny, So sorry to hear of this new health issue for you.
I have an autoimmune disease called 'Polymyalgia Rheumatica' and have had it since my early 40's. With this condition I have been having Bone Density Testing done every two years as a precauton with the daily doses of Prednisone I take. Since having had BC my last test showed that my bone density was slipping slightly in comparison to previous testing. I asked was this due to the chemo? But they said it wasn't necessarliy the case! I have this test done on the same machine each time which allows for a better diagnosis as they do vary I have been told. So make sure you go to the same place if you can because the doctor told me this way they are comparing you in the same way as before. This will pick up your changes a lot easier. My Mum had osteoperosis too which was quite painful for her. In saying that my Mum wasn't the fit and lively person that you are, so I am sure you will take this minor set back in your stride!!!
I hope you continue your journey with the same positive outlook you have always had hun. GOOD LUCK!!! XXX Mia.