Long standing SI Joint pain. Remedies.

2years ago, I was diagnosed with sacrolitis. Ever since, there has always been a burning sensation on the immediate left lumbar spine and the si-joint always seems inflamed /painful. I was redirected to a rheumatologist. My HLA B27 negative, ESR, CRP normal, MRI showed chronic sacrolitis. Initially I was given Saaz DS for 3 months, then biologics like Adalimumab and Etanarcept for 3months each with regular physio, walking, hot compress. But I didn't respond well to either of them, my pain continued to linger at same intensity. Rheumatologists cited it may not be an autoimmune disorder and it may be mechanical in nature. I had a steroid shot into the joint itself but that didn't give any relief either. I have been doing physio under a trainer for the past 3 months, in strict diet control to avoid inflammatory foods, but still I feel extreme pain near my hip si joints and burning sensation near the left lumbar spine. I am barely able to sit 20 mins stretch. Please suggest some remedies.