I have problems with various symptoms in my feet including the burning sensations you describe. I saw a neurologist who did some electrical tests and confirmed I have a peripheral neuropathy. Given that I also have some kidney necropathy too in the early stages my specialist thinks I must have been an undiagnosed diabetic for 5-10 years before diagnosis. I never used to bother with docs etc thinking oh well I am young and healthy just ignore it and it will go away. Problem is this has obviously caused damage in the meantime, I dont know your history but maybe you have a similar thing, Although you cant rule out stuff like a bad reaction to your medication might be worth discussing trying something else just to rule it out. I know the nurse I spoke to at my employer's occupational health provider told me that metformin can sometimes cause a lot of aches in muscles and feet etc and sometimes people are misdiagnosed with more serious conditions as this is not checked at an early stage.
