Hi, Welcome to Health care magic forum.
It appears to be the brusitis, it only progress faster, For
arthritis it may not be the time. Other causes may be the disc problem, and
sciatica, which are seen in the old age.
The other possibility may be the
renal colic, due to stone in the
ureter , which will be deep, and does not change with the posture.
I advise you to consult an orthopedic surgeon for diagnosis and treatment.you may need to have a
MRI for diagnosis.
Avoid giving her potato, other tubers, tomato, egg, chicken, and sea foods till the pain is cured.
wishing for a quick and complete recovery. Thank you.