What Does Severe Pain In The Lower Back Indicate?

Yesterday evening, while bending over giving my daughter a bath, I tried to stand up straight and had a sudden extreme pain down the lower half of my spine. At the time of the incident it felt as if a tight string down my spine had been plucked and caused shooting severe pain from my tailbone up half my back alone the spine. It pain continued all night and is worse today. I have extremely limited movement and the pain is constant without moving but worse when I do try to move. I am unsure if I pulled a muscle or something worse, or if I should go to the hospital. P.S. I can not take any kind of pain medication.