Breast cancer and bones

After primary cancer with the works! I had Fosomax with no side effects and improved bone density after 5 years. Since mets in bones diagnosed about 18 mths ago, have tried Bonifos (didn't like dosage & inconvenience - 2 large tablets & one hour of inconvenience), then Bondronat (1 small tablet & half hour of inconvenience), neither of which appeared to cause any side effects. (I'm also on Arimidex & took Tamoxifen for 5 years after primary cancer.) I decided to make life easier with a once a month infusion of Zometa to replace tablets. After the 3rd infusion it was obvious that it was indeed the Zometa setting of severe pain (really debilitating) in my upper back where I have no mets, but some bone degeneration/osteoarthritis - not debilitating nor even noticeable normally. Apparently no one has ever had this reaction - the flu-like general aches were gone within a day or two while the back pain took almost the full month to go. Ever heard of this happening? I'm happy to be back on the Bondronat with no back problems, again. Nellie