I'm sorry you have tried so many things with no relief. I know a little bit of what it is like, as I have had back pain and sciatica for several decades and like you, I have tried many different treatments, including chiropractic, various types of massage, spinal injections, traction, TENS unit, physical therapy, exercises, and medications.
Most things were helpful, for a spell, but none were a cure. It sounds like Button's surgery is the closest thing to that. Are you, and your back, a good candidate for surgery?
You might still want to look into trying a full series of traction sessions with a good physical therapist. Theoretically, at least, it does a similar thing as spinal decompression. It benefited me enough that I realized the value, for me, of making sure I do certain spinal stretches every day and whenever it worsens between times.
Fair warning, though, is that traction can cause even more back spasms, especially at first, which for me required other treatments before and after, including more medications and muscle relaxers. But that gradually subsided a bit during the course of therapy, and really, since I already had so much pain anyway, a little bit more isn't that big of a deal, if it actually helps the healing process.
I should say, I also do other things to help my back. We keep a firm pillow (that I made) in the car at all times, which I use as a footrest when I need one at restaurants, etc., because the height of most chairs hurts my back. In the good old days, I was able to borrow phone books from most places and use them for a footrest, but phone books have gone out of style. I also lean forward in bad chairs, or sit on the edges, put my legs up, or stand up instead, although standing poses its own set of problems for me.
I also use custom arch supports, and orthotic or well fit walking shoes nearly all the time (I really pay for it when I occasionally wear other shoes). We did a ton of research on mattresses and mattress pads and have the best setup for my back. My office chair set up and keyboard are all optimized for ergonomics. My hairdresser adds cushions to the seat and adds a foot rest when I am getting my hair washed, to spare me from additional pain.
In short, as you've probably discovered yourself, back pain is something that can affect every minute and every movement we make, every day. If you haven't already, although I'm pretty sure you have, so this advice is more for other folks with back pain who have stumbled upon this thread, look at every single daily routine you have, and see how it can be optimized for your back. I have found every little tweak I've made to be worth it in alleviating some of the pain.