Hello Dr. Rynne, I began experiencing a sore tongue and tingling of the mouth, face, and for a while, the scalp, with fatigue developing over time. They began after I ate some box mix cornbread that had a very strong sting in my mouth. The symptoms decreased dramatically for about 2 months after I stopped drinking reverse osmosis water (highly acidic) but have reemerged within the last two weeks. I am diabetic and have been taking metformin for 19 years. Blood tests showed a normal blood panel in November. Thanks, Helen