Hi, Welcome to Health care magic forum.
As you describe, it may be the
arthritis, or some problem with the vertibrae or discs.
She is becoming fatty, it is O.K, most of the pain killers will have the weight gain as a side effect.
If the pain is not controlled, I advise you to consult an orthopedic surgeon for diagnosis and treatment for her.
She may need to have an M.R.I and other tests for diagnosis.
I usually prescribe to my patient with such symptoms injections of
vitamin B1,6,and 12 for10 consecutive days, and then periodically.
protein supplements, calcium, multivitamins,
diclofenac, and
paracetamol.
What you are thinking weight gain may be the edema.
I prescribe diuretics for such edema.
Avoid taking potato, other tubers, tomato, egg, chicken, and sea foods.
Wishing for a quick and complete recovery. Thank you.