If considering the recent study, often 'slipped' (or prolapsed) disc causes the sudden severe lower-back pain. Disc often presses on a nerve root which might cause pain & other counter symptoms in the body. In most cases, the symptoms start to ease off gradually within few weeks. Thus the usual advice would be to carry on as normal as much as possible as you can. Of course, painkillers may help to reduce this; But physical treatments such as spinal manipulation may also be helpful. In case if the symptoms persist, the surgery might be counted as an emergency option.