By your history, it appears that you have had a discectomy at L5-S1 two years ago and surgery was a success as the pain disappeared initially. I am unclear when the pain returned, but apparently it did at some time. The pain now is intermittant in your right buttocks. The pain is aggrevated by bending and sitting. You do not report any back pain.
This is speculation but by the sounds of your symptoms, you may have a recurrent disc herniation at the same location as your first herniation. The chance of that occurance is 10% in the active population.
Without significant back pain, you don’t need to think of a disc replacement or a fusion. What you need is a diagnosis. Either go back to your original surgeon or find a spine surgeon with a good reputation and ask to be looked at. You most likely need a new MRI with gadolinium (the dye that lights up scar tissue) to determine what the next step is.
Donald Corenman, MD, DC is a highly-regarded spine surgeon, considered an expert in the area of neck and back pain. Trained as both a Medical Doctor and Doctor of Chiropractic, Dr. Corenman earned academic appointments as Clinical Assistant Professor and Assistant Professor of Orthopaedic Surgery at the University of Colorado Health Sciences Center, and his research on spine surgery and rehabilitation has resulted in the publication of multiple peer-reviewed articles and two books.