Hello,
Thank you for your query at DoctorSpring.com
I have gone through details of your question & x rays.It looks that your mother is having a john's fracture at base of 5th metatarsal bone.This fracture is mildly notorious for non healing due to attachment of tendon .It will be better for her to have it operated.It can be fixd easily by an orthopedic surgeon by screw or tension bend wire.
Hope this will help you.
With best wishes.