I have been in Prolia for 3 years and have had no GI nor muscle issues. I have never had any side effects with prolia. Fido max was totally in a payable with my GI Issues; thus I was switched to Prolia. I always hydrate well prior to the administration as it is important to do so.
Hope you find a resolution.

I have IBS and took Fosamax several different times in past years. I believe I probably took Fosamax for about four years or more the first time my doctor prescribed it and had digestive discomfort that can best be described as ulcer-like pain. It didn't last long, just a few hours, but would occur each week when I took the Fosamax. I eventually took a break from Fosamax for about a year and a half, and then was persuaded by my doctor to start taking it again, which I did. I took it for about a year, but due to pain in my legs, upper thighs and groin area that was quite severe, and especially at night, I stopped using it. I had aching in my bones that often had me walking the floors at night in pain - it scared me! I stopped using Fosamax after the pain became more persistent and after hearing all the media medical reports, reading the side-effects of other's who were using Fosamax/other osteoporosis drugs, and doing extensive research on my own. The digestive issues were not the reason I stopped as they were tolerable and the pain in my legs and groin were much more of a concern. My numbers also unfortunately, did not improve greatly at anytime while I took Fosamax. It's been some time now since I stopped taking osteoporosis drugs and I feel great, but do eat and exercise for bone health. I in no way suggest that anyone would experience what I did taking Fosamax as we are all different, and Fosamax or another drug may be very beneficial to someone else. If more safe and effective drugs become available in the future without numerous and serious side-effects, I would consider them.