Hi Alex, thanks for sharing. I've tried fermented foods (made sauerkraut & kefir) before but not at the level you're describing.
I was able to get total remission of my AS with the carnivore diet (100% meat) last year, but it fell apart if I cheated even a tiny bit, and was too monotonous and antisocial to sustain. It remains an emergency option for me if my AS ever gets too bad / untreatable later in life. It took 3 months of being strict with it for it to really give me any relief though, and I definitely didn't cram fermented foods every day for 3 months when I dabbled with them.
I am not on Anti-TNF, however I might be able to get on them next year, and also the symptoms you describe in 2018 sound worse than mine - I still have periods with no pain / flare ups, however I can't exercise barely at all without triggering a flare up.
You've inspired me to start a load of krauts & veg, kefir and sourdough going, to give them a massive try in a month or two. Please let us know how it goes if you stop the anti-tnf