@maymore hello. I just started taking Tymlos 5 days ago. On the very first day that I took it, I had that exact same spasm in my lower back. I do have degenerative disc disease of the lumbar/sacral area (wear and tear of the spine from aging). I am 61. But that pain was real. It subsided in 30 mins or so. And also got better in the next few times. I told my Endocrinologist about it and his response was that he had never heard of this reaction from his other patients. Glad to know I was not just imagining it.
I plan on continuing with the med.