Continued pain three months after a decompression/fusion should be looked into for source. This would require at least a new MRI and possibly a new CT scan. The possibility of chronic radiculopathy (see website) has to be entertained but this is a diagnosis of exclusion (everything else has to be ruled out before this diagnosis can be made).
Your anterior thigh pain and numbness could originate from the L2 or L3 nerve. This could also be meralgia paresthetica (see website).
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.