I have lots of lower back issues and for me the best remedy is stretching, the most important/effective stretch (for me) is knee to opposite shoulder. Not to rule out strength training. My first physical therapist was mostly focused on strength training (planks and such) and a later PT was mostly about stretching, and the stretching turned out to be a "eureka" discovery for me. I think you have to figure out what works best for you, and don't be afraid to try different physical therapists and different approaches - experiment.