What kind of pain is it? Is it isolated to your back or does it radiate (down your arms/legs)? There are certain body mechanics that can help-physical therapy is a good place to start. They can teach you certain exercises and stretches that can help. Regardless, you should probably see a doctor to make sure it's nothing serious, then they can guide you as to next steps. In the meantime, heat always made my back feel better (others prefer ice, so see what's best for you!). Over the counter anti-inflammatories (Naproxen, ibuprofen) can help-it's worth a shot. If your desk at work isn't great, there are cushions you can buy on amazon (like this one that will help with keeping your posture and give you additional support. Remember to try and take breaks when you're working (I'm guilty of this, too). Sitting for hours on end at a desk can do a number on your back, so even if it's just to get up and stand for a few minutes, it will help.
That's all I can think of for now, I'll comment again if anything else comes to mind. I've been there-I know how much it sucks. Sorry to hear you're going through this. Hope you find the relief you're looking for!
Edit: spelling