Unfortunately, without seeing your MRI myself and knowing more history such as your preoperative signs and symptoms, how you did right after the surgery and up until the onset of pain, the actual type of surgery (with or without hardware placement), complications post-op, and preop MRI results, it's extremely difficult to give an accurate opinion. WHat I can say is that the epidural scar tissue formation, hardware displacmemt (bad or loose screw), infection at the postop site, the L5-S1 disc, orrecurrent disc bulging are all possibilities. My guess is that it has something to do with the epidural scarring or fibrosis on the right side. One consideration is talk to your neurosurgeon and see what they think in terms of the need for going back in there and cleaning it out or just watching an waitin. ANother possiblity is for you to get a second opinion and bring in your films for their personal review. Treatment really depends on the cause and unless the cause is determined, you can just treat symptomatically with pain meds like neurontin, NSAIDs or even light physical therapy or rest. Talk to your neurosurgeon about your concerns and let them know you are in severe pain. You may need to see a pain management doctor to help you out until they figure out the cause. Good luck.