My patient had a sore mouth, but I couldn’t really see anything in particular that could be causing it.  

We tried a course of antifungal drops, then lozenges, on the off chance it was thrush. She also had peripheral neuropathy, but that was longstanding ever since chemotherapy and a bone marrow transplant for non-Hodgkin’s lymphoma decades ago.  

However, the pain in her feet was worsening. She felt weak and her balance was now impaired. She also seemed quite depressed and had lost her motivation.  

I looked at the differential diagnosis of a sore mouth and among them was burning mouth syndrome. I had never heard of the ailment, but autoimmune and vitamin deficiencies could be implicated.