I still have concern here. A "through examination" should include at the very least an x-ray - particularly if the vet is thinking the problem is related to a disc. Just like human docs, there are good and bad animal docs. Homeopathic medicine definitely has a place, but in my opinion, it should not be the only treatment. If at at all possible, I hope you can convince your mom to consult with a vet who also focuses on western veterinary medicine.
You may also want to consult Dr. Cheng here at Med Help on the Ask a Vet forum. She practices both western and holistic veterinary medicine and I'm certain she can give you some insight on this subject.