The pain could be from scar, nerve entrapment (foraminal collapse) or recurrent herniation. Make sure you have gadolinium with the MRI to help delineate what is scar and what is bone or herniation.
The nerve block increase in pain could be from a multitude of problems. Some injectionists inject the fluid bolus too quickly creating a pressure “wave” which can cause a pressure phenomenon. Some inject into the nerve itself which can be quite painful (the fluid is designed to “bathe” the nerve by surrounding it). Rarely, just the injection can be irritating. The big question is were you told to pay attention to the first three hours after the injection (see pain diary)? This time is the diagnostic window and many injectionists do not have you aware or record the pain in this period.
Disc fragments commonly are associated with discal spurs (bone spurs that project our of the corners of the disc space and are associated with the annular tear that is the reason for the herniation in the first place).
There is a possibility that you have chronic radiculopathy from the original compression but that is a diagnosis of exclusion (rule out everything else first).
Dr. Corenman
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.