Hi Lisa,
So sorry to hear about your Mom. This is NOT the beginning of the end based on what you've said here (but it may be time to get some second opinions).
How is that the doctors knew that your Mom had cancer for 7 years that went undetected?
I'm assuming that if she was diagnosed 15 months ago and underwent a transplant that she must have had imaging done in the past year that didn't show any fractures?
Also, are you working with a doctor that specializes in multiple myeloma and are your confident all of her numbers are good and that her multiple myeloma is indeed not active? Some of the key hings you would be looking at to see if she was active or not would be her M-Spike from her Serum Protein Electrophoresis test, her freelight chain levels form a Freelite Assay and the results of a bone marrow biopsy test.
Assuming all of her current multiple myeloma numbers truly are good and her earlier images were clean, I'm guessing that her bones might simply have been compromised earlier by the myeloma, but are now just fracturing.
You might want to discuss a procedure known as kyphoplasty with the doctor. This is often used to treat multiple myeloma patients who have fractured their vertebrae. It's actually a fairly simple procedure and has provided a lot of relief to multiple myeloma patients with fractured vertebrae over the years.
http://www.spine-health.com/treatment/back-surgery/description-kyphoplasty-surgeryYou might also want to discuss the use of a bisphosphonate such as Zometa to help with the bones
These are just a couple of ideas. I'm not speaking from direct experience in this situation, so others on the forum that have been down this path personally may have some different thoughts.
Best of luck to you and your Mom.