In reply to James Malloch:
I've had a number of issues over the years, due to sitting using a computer all day. Essentially down to bad posture. An assessment of my posture, workstation, and a split keyboard and joystick mouse fixed them although I'm now experiencing some different problems due to the mouse...
Sitting badly at a desk is dangerous, and I've had words with our H&S rep about our graduate intake, and their tendency to slump in their chairs...
Not sure if this s your problem, but it's worth thinking about.