New X-rays would be helpful to make sure that the fusion is going well and the instrumentation is well placed (no loosening). The radiculopathy increasing is important as at 3 months, the leg pain should be diminishing. If your physical examination is unchanged (no increased sensory or motor weakness and no increased tension signs), then a short course of oral steroids could be helpful. If exam signs increase, a new MRI would be helpful. I assume you have no fevers or chills.