A seventy years old lady started sudden acute low back pain, unbearable. X-Ray showed advanced degenerative spinal changes. MRI show narrowing of IV spaces. Mild bulge of IVD at L4 -L5 and L5 -S1, on palpating acute tenderness over left sacroiliac joint almost unbearable.

Treatment with muscle relaxant and paracetamol has not helped. The patient is unable to tolerate other painkillers like Diclofenac etc. What should be the line of treatment?