Hello,
Thanks for your query at DoctorSpring.com
I have read your question with diligence and checked the x-ray.
It looks from details that your mother is having problem of listhesis at lumber 5 and sacral one vertebrae. It means that there is displacement of L5 vertebra over s1 vertebrae.
This needs complete evaluation by having MRI scan of spine.
I am sure this is leading to stress over spine and compression of nerve by disc.
You may have consultation with a neurosurgeon in this regard.
Hope this will help you.