The numbing agent works for about three hours. The relief that your husband received is most likely proportional to the pain generation that the shoulder generates. Since the block was performed at 4:30PM and his pain returned at 9PM, the block had worn off by then. His shoulder is at least part of the problem.
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.