I have had 4 screws, 2 pins, and a new vertabre put in my lower back 6 years ago in July. I did some yoga classes, and the last one was on Tuesday, and my back started to hurt on Sturday. I started a new job and it intails some lifting. after 4 days of this, while lying on my back, on the floor, I put my hands under my lower back and hurd and felt grinding. Can I have loosend or broken the screw? I m a 67 year old female in very good health.