lower back pain

I had back surgery 4 weeks ago. I was having pain on my left side and down my left leg. The mri report showed spinal stenosis and the s1 nerve was pinched and I also had a fragment floating in the space. My doctor told me that the nerve was pressed flat when he did the surgery and that he had to do quite alot of bone removal. My problem is that since then I have been having a burning pain in my right side and cramping down my right leg this has keep me up during the night. I don't know what to do.