Jumping in to this late, but hopefully I can help anybody still suffering like I was.
Some history, I've suffered with a bad back since my 20s (I'm now 41), and was diagnosed with a slipped disc about 3 years ago (no coincidence that we had just had a baby). It gradually eased with use of naproxen, but came back a little while after my wife had our last baby (just over a year ago).
I had a feeling that my sofa wasn't helping, so started using a proper armchair (not a 3 piece suite chair, a solid wood chair). I can't describe how much better my back is now, it is almost as if I've never had a problem. My wife doesn't like the chair, it looks like we have an old person living in the house, but I remind her that without it, I pretty much WAS an old person.