sue417,
Sounds like this is exercise triggered and might settle with a lidocaine, either patch or injection. My sister would have lidocaine injections in the taut muscles. They are easy to recognize manually by the practitioner. The effect of lidocaine is brief about 6 hours, but the spasms, once interrupted, wouldn't return until they were overstressed again.
I'm hoping it isn't another fracture.
I'm impressed with your exercise routines, maybe enthusiasm over the new back machine overworked those muscles.
The patches are otc in drugstores. But I think the injections are better.