This color change associated with slight burning could be a mild case of CRPS (complex regional pain syndrome) which previously named “RSD”. See https://neckandback.com/conditions/complex-regional-pain-syndrome-crps-reflex-sympathetic-dystrophy-rsd-causalgia-neck/
This also could be some residual from the cauda equina syndrome.
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.