Hi, a little over two weeks ago my lower back suddenly started hurting, no sore muscles, just a sharp pain when doing just about everything in lower back. it feels like a knife stab in middle, lower back, a hand or so above tailbone. it just happened..any thoughts? i m 6 2 , 215lb, VERY muscular , 11% bodyfat, cholesterol, triglycerides, all that stuff is normal. i m not diabetic. just a 19 year old guy wondering why the heck my back is hurting. in the past if something hurts, even severe, a few days and its gone, or dull. any help on this please?