Been Taking 70 Mg Alendronate Wkly For Over 4 Years

Been taking 70 mg alendronate wkly for over 4 years now. Bone scan a couple months ago showed a decrease in CA in both my spine and hips over the original scan in Oct 2012. Wasn't surprised by original diagnosis as didn't get much CA in my diet in early 20's, but doctor says my bones aren't absorbing CA now. I don't get that and don't know other options. She only suggested semi-annual prolia, but I also have cutaneous lupus issues that I've only recently gotten under control as well as tingly already in fingers and toes for other reasons. Side effects seem problematic under the circumstances. Suggestions?