Your pain pattern sounds like bone pain (pseudoarthrosis) but if a solid fusion is present, it could be hardware pain. The CT scan will be very important to review as it sounds like you have lack of fusion. You might need an ALIF to repair your spine.
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.