muscle spasm
"I never had any back problems until I reached my upper 40s. If I wasn't careful, I would somehow manage to pull my lower back muscle. The pain was relentless, and nothing I took really helped; it only took the edge off. Very fortunately, a doctor recommended I take Skelaxin/Metaxalone, and FINALLY something helped! So now I always keep a bottle in my medicine cabinet, just in case! The only downside is that it causes constipation, but I just make sure I eat extra fiber & drink extra water."