Sponge feet sound like Peripheral Neuropathy, which is what I have, and if so you should definitely tell the Consultant.
The worst thing you can do is ignore Myeloma so you must also inform the Consultant that that is what your mother is trying to do. I know exactly where your Mother is coming from my Mother in Law was made of the same stuff, a great old girl who I loved dearly.
Helen?s advice is right, speak to our resident Myeloma UK Nurse she will help you. Be strong.
Kindest regards ? vasbyte
David