What Causes Iliac Crest And Lower Back Pain?

Good Evening, I have had ongoing lower back pain for a longtime. Mainly I experience almost constant pain around the top of my iliac crest. Tender to touch, pain on bending to the side etc. I do a variety of stretches, have seen numerous physios, chiropractors and nothing seems to relieve the pain. I have had a MRI as a precaution sometime back: L3 - L4 and L4-L5 discs degenerate and posterior disc bulge, l5 - S1 - no focal disc herniation. No significant facet joint hypertrophy. What I am seeking is the best option to get a 'proper' diagnosis, so I can manage the pain etc. Thank you