This is my old enemy, sorry I didn't see this before. My very worst was 2 slipped discs which trapped the sciatic nerve in 3 places. At this point I was offered surgery but opted for treatment by manipulation from a dual-qualified phsio/osteopath. It took him 6 months, but I got better. That was in France.
It started up in UK a year ago, I took (French) X-rays to GP to explain condition of my back and was referred to (eventual) physio, who did no manipulation and asserted that the aim was to enable me to 'manage' the pain. Rubbish! I do the exercises anyway - and have done, for ages.
Only way out was to find a good osteopath (for whom I have to pay privately) and after beginning with 2 sessions a week I am now down to 1 every 2 months and the aim is for one session every 3 months to keep me walking and out of pain.
I strongly suggest that you follow this route. (I've tried almost everything else.) Good luck :)