Most cases of back pain aren’t caused by serious damage or disease but by minor sprains, strains or injuries, or a pinched or irritated nerve.
These types of back pain can be triggered by everyday activities at home or at work, or they can develop gradually over time.
Possible causes of back pain include:
Back pain sometimes develops suddenly for no apparent reason. For example, you may wake up one morning with back pain and have no idea what’s caused it.
Certain things can increase your chances of developing back pain. These include:
In a few cases, your symptoms may suggest a specific medical condition is causing your back pain. For example:
Rarely, back pain can be a sign of a serious condition such as a spinal fracture, an infection of the spine, or cancer. If you see your GP with back pain, they will look for signs of these conditions.
Read More About: Diagnosing Back Pain.
Source: NHS UK
http://www.nhs.uk/Conditions/Back-pain/Pages/Causes.aspx