Have you addressed your sitting position at all?
When you need to sit for along time taking a short break every hour is key. Getting up walking to deliver something to another in your office is an example.

Have you looked at your sitting position?
Episodes which address the impact of sitting on your body.
Why Sitting Wrecks Your Mad Hip Action
Episode 276: MobilityWod Google Talk: Desk Bound
Episode 251: High Skilled Sitting/Abdominal Bracing
Episode 187: Death by Chair. How Much Do Actually Sit?
Episode 91: Mobilize In the Position of Death by Chair
Episode 88: Desk Athlete Hip Rescue
Episode 15: You Must Defeat The Evil Chair Part 1
Episode 15: You Must Defeat The Evil Chair Part 2