Hi goodnugg!
When eating a low carb diet, your tongue can get coated in the back. I would try brushing your tongue when you brush your teeth. Then use some mouthwash. Consider brushing more often than twice a day. Listerine has also marketed a strip that you can put on your tongue to freshen you breath. I can't imagine that it contains any carbs. It tastes just like listerine. It good for a quick breath freshener.

Good luck