I have been plagued over the past few years with a sudden onset of low back muscle spasms, so agonizing that I literally cannot move. Previously, only 3 days of bed rest on my back with a pillow under my knees helped, along with pain relievers and Valium to relieve the spasm.
What I realized was that, when standing, I was so afraid to tense my back muscles that I was hunched forward, putting my back muscles under even more strain. Then I tried wearing a backpack with 6 liters of water in bottles in it. Instantly I stood up straighter. Being counterbalanced with the weight of the bottles, my back extensor muscles could relax. The pressure of the backpack hanging low over the muscles was like having a constant massage also. I could finally walk around without pain.
Holding onto one ankle at a time and bringing it up as high as possible while extending my hip backwards also helped enormously.
I still have spasms now and then, and they still take three days before I feel completely right, but I no longer live in fear of them. - Simon