My father has burning sensation in both his feet in the last 30 days. This has happened even before in the last few years and it doesn't stay long. He is 86/-. He is not chronic diabetic or heart patient. But consuming glyciphage for the last 15 years. At present he takes olsar 40 mg twice in day. glyciphage ,doxovent, pregabalin 75 mg, prothiaden 25 mg in a day. But it is not seems to be subsiding. What could be the reason for it?