Hi Ana,
Let's think about this. You said your back spasms are worse when laying down and sleeping. You are not a large person. You said 127 lbs and 5'4".

Could it be your mattress? Maybe some extra padding, better support, or a Memory foam topper? Just a thought. When I lay down I wake to these pains too.

Since I bought the foam, 2 inch topper, the bones that stick out on my back get relief. I have large bones, but I am thin too.

Just thinking of other ideas. I hope you feel better soon.