I'm sure you will get a lot of input and comments on this so I'll keep mine short. Do you have referred pain? meaning anything else outside of the spot in your back? ie. back of thigh or calf, buttocks, hip?

Yes, I had this same kind of spasming for many years. The only way I could get them to stop was to do physical therapy, apply ICE as a heating pad only made it worse with long term use. Relief was temporary with heat and the relaxation would cause muscle tone to be lost. The best exercise I found was to swim as the buoyancy of being in water relieved the stress on the joints and muscles all over my body. My eventual solution was not any I'd wish on my worst enemy. The spasms were due to my spine becoming arthritic and were my body trying to protect itself. Eventually I had to have three surgeries to my spine and a fusion of the vertebrae in order to keep my ability to walk and still there is pain. And narcotics do not control it at all. They only help to make it tolerable for a short time. Good luck with this

I've had such luck with chiropractics that I'm suggest a visit to one. It isn't just that chiropractics can often offer a quick fix, but they can explain cause especially if the cause is positional as yours seems to be. Another advantage is that you can usually be seen same day.

Hello @ksdm, I combined your new discussion on back spasms with your existing discussion "Mid-back muscle spasms" - https://connect.mayoclinic.org/discussion/mid-back-muscle-spasms/ - so the members you met and discussed with would see your new post and update.