https://www.dropbox.com/s/pr7m4senrl71ua6/Screenshot%202017-05-24%2018.32.00.png?dl=0
I've had this for at least several months. I have excellent dental hygiene (cleanings biannually, use mouthwash twice daily, tongue scraper, electric toothbrush, etc).
I always seem to have a somewhat bad taste in my mouth after brushing my mouthwash wears off or within an hour or so after eating and I believe it originates from my tongue. I only drink water (no soda, sugary drinks, etc.