You may have just inadvertently revealed the source of your back problems in this post! Your problem could be that you're bending over to grab stuff. You should almost never do forward bends at the waist. Think about how many times a day you may be doing it. If you keep doing what is aggravating the discs your issue will never go away... doesn't matter how much PT or exercise you do.I'm dealing with it now. I have issues in the same zone. Mine flares up pretty bad once or twice a year. It's at its worst after a prolonged absence from surfing/exercise then going in cold.
This time, I hadn't surfed in a few weeks, I started back at work (2-3 hour round trip commute), tried to jump out and surf in the afternoon after sitting in meetings all day. Stretched for 4-5 minutes before (which doesn't do all that much), paddled for 30 minutes, stood up on my first wave and did the infamous "bottom turn- to grabbing the small of my back- to go straight in".
Laid me up for a week, rested, iced, anti-inflammatory and muscle relaxer at night, travelled to Portugal feeling pretty good, and the day we were going to head to the coast I reached onto the floor for a napkin and BOOM. locked up again.
Now we are in the season for waves at my local and I'm on the IR.
Lacrosse ball to the muscles in my back, glutes, PF, hip flexors, etc, stretching the hammies every which way, bridges when I can, gradually increasing activity, and avoiding a seated position as much as possible has been the only way I get past it. Upping your core fitness routine is the only real way to deal with it. I've worked with PTs and Chiros. Good ones are worth their weight in gold, but most of them are average or less. Finding one that surfs or is active with athletes is a game changer. I'm still on the hunt for one in SF.
and yes, underlying disc issues are often a problem.
Here's what I'm talking about.