I went through something similar the past couple of years, and was letting my back determine job prospects (i.e. I didn't want to take a train downtown and walk five blocks to work, hell I didn't want to walk to the parking garage next to my building).

For me (and possibly only me, I don't know your situation), what worked better than anything was to start eating a keto (low carb, and incidentally no wheat) diet, which some attribute to having anti-inflammatory effects: http://www.wheatbellyblog.com/2012/01/low-back-pain-chiropra.... The pain went away very quickly (for me within a week of starting the diet) and I can walk normally again.

I'm not saying it will work for you, I don't know, but I've been on the diet for four months now, and the pain hasn't returned since. You might want to consider it. It significantly improved my life. I also lost 40lbs as well in that time period, with not a whole lot of exercise, which I'm hoping will help insure the pain doesn't come back in the future.

It's awful and it dictates your life when you have it, I know. I hope you figure out what's wrong and find something that works for you.

Also, if nothing else, I noticed that I could stay in the pool pretty much as long as I wanted when I had back pain, due to its buoyancy effect, so when I did have back pain, I got my exercise in by going to the pool regularly, and found relief from my pain while I was in there. You might want to consider that for weight loss as well.

If you are interested in keto, check out http://www.reddit.com/r/keto. It's a great source of information, motivation, and similar stories such as mine by real people, not paid endorsements.