Sitting can definitely aggravate that existing back pain. For work, it sounds like a standing desk that can also decrease in height for short periods of sitting is a good option. At home (and in the office) you can try alternating from standing, sitting, stooping, squaring, and kneeling. You may also need to try a foot rest! Also, if you haven't seen a doctor about the chronic pain, that is a good place to start. They can provide you with a physical therapist that can give you some good pointers and stretches to help.