Your history is typical for your lower back pain. Pars fractures that cause spondylolisthesis normally occur between the ages of 8 and 15 (see website for further explanation). Pain in the lower back is not unusual for this disorder.
Your neck pain is a different story. You apparently have multilevel cervical degenerative disc disease (pretty much the same as “degenerative changes”). This can cause local neck pain and stiffness. The facets can also cause neck pain and stiffness (see anatomy of the cervical spine, degenerative disc disease and degenerative facet disease also on the website).
Hopefully, your doctor has started you on a rehab program and has suggested various medications to help. Chiropractic care could also be considered for treatment for your neck.
Dr. Corenman