Most types of back pain are not a medical emergency and can actually be treated by pain killers, physiotherapy, exercises and occasionally surgery.
However, you should really know the symptoms of a back pain which could be a medical emergency.
Some symptoms to take seriously are leg pain which progresses to weakness and/or loss of bowel or bladder control. Unexplained weight loss with pain. Acute, severe stomach pain along with low back pain so bad that you cannot stand straight, and a fever with increased pain which does not get better after taking common fever reducers.
The symptoms of progressive leg weakness and loss of bladder/bowel control plus numbness in the groin or area of contact if sitting on a saddle, could be something called 'Cauda Equina Syndrome', which is usually caused by a compressed nerve in your lower spine.
Always visit your GP or emergency department if you feel your symptoms are in any way similar to the above or different to your normal pain.