How old are you?
Pain in the lumbar joint can be due to degenerative changes in the joints which occur in old age.
Other causes include rheumatoid arthritis, ankylosing spondilitis, osteoarthritis, and rarely synovial cysts and infections.
I would advise you to please schedule an appointment with an orthopedic surgeon and undergo a complete clinical examination and tests like X ray and CT scan.
Do keep us posted!