Severe lower back and buttock pain. Hlp!

Hi doctors I have severe lower back and and pain in buttocks (actual towards side of buttocks) since a month . I am not able to straighten my back . If I bend a little forward I feel a bit relieved. Based on these symptoms my Ortho had guessed this to b ankylosing spondylosis. HLAB27 test was on borderline positive. I went to rheumatologist with these results. He Suspected this to be axial spondyloartritis. So put me on medication with Zycel 200 for 15 days. After 15 days my pain was still there , so he asked to stop this medication and get HLAB27 test with PCR method , the results showed negative. ESR and CRP values are normal.  I am waiting for MRI results. Last mid night, I had an accute pain , I literally cried without bearing the pain. I am not taking pain killers. I do physiotherapy regularly but efforts are in vain. Today the pain started shifting to other leg . I m in very bad pain . Any suggestions to get rid of this would be appreciated . tnx for reading this .plz hlp