Sympathise OP & reading with interest. My left lower back has gone a few times over the years, probably as a result of doing a forestry job in my 20’s and early 30’s. Unbelievably painful when it goes, can’t walk. Dose of painkillers and gentle exercising usually gets it back to normal but like others you forget to do the stretches when you feel ok. I once sneezed when shaving and that put it out.
2 years ago I busted by left foot and recently had an arthroscopy on it which seems to have worked on the foot, but the awkward walking over 2 years now gives me almost constant pain in the same left lower back/bum/groin area with shooting pains down the leg. Doc has given me Naproxen and am on a waiting list for physio. In the meantime trying to do exercises recommended by him but I think I might be overdoing it as no improvement. I can still ride my bike, just getting on and off is the problem. I have a small insurance policy so could get a few private sessions of physio whist waiting for NHS (not sure if I need osteopath, chiro, sports physio or what) but am a bit wary going on what others have said above.
Very frustrating pill popping but I guess you get there in the end.