QL & Iliolumbar Pain

42 yo male in very good physical condition. Participate in functional fitness routines 5-7 days a week. Over a year ago I walked up the stairs to my office and experienced pain in the QL and iliolumbar region of low left back. Did not recall any trauma that could account for the pain. Pain would only present when climbing stairs, bending over frequently, sitting or standing for long periods of time. Could also get pain to present by leaning back. Never extreme pain just a pinching pain when doing the motions. I could workout and run with little to no pain except when performing exercises that require bending over at the waist for multiple reps. I continued for a couple months thinking I had strained a muscle and it was just taking time to heal. I iced and took anti inflammatory during this time. I then went to Dr and received a steroid shot and was on a stronger anti inflammatory for 2 weeks. At that, I went to chiro for 6 wks with little to no change. I then went on to PT and did 6 weeks of core strengthening, a dry needling session and massage therapy. Pain had subsided from QL region but would still come and go around iliac crest right above left belt line. Occasionally, I would feel it over in the hip area. I have been very intentional on doing functional core work and treatments as prescribed, but still cannot overcome pain completely. It will get really irritated when doing yard work, house work, sitting and standing for long periods, but will subside quickly with rest. I have not returned to the Dr or PT and have not had an MRI. After some research I suspect it could be an issue with the iliolumbar ligament. I’m wondering if there’s any exercises or treatments that could be recommended to try further help or identify this issue. Thanks for your time.