I would definitely recommend diatomaceous earth. It totally solved this issue that I had struggled with for years. I started in October 2018 and took it for six months until the whole bag was finished. I haven't had a problem since and from the first time I took it, my therapist, who would often mention the problem to me, told me he smelled nothing.
This is true! I suffered for 25 years until I heard about the food grade diatomacious earth. I thought nothing would help and believe me I tried every mouth wash, gum, you name it! It was bad! After one day of taking just 1/2 teaspoon in water, it solved my issue like a magic trick. I couldn't believe it! My life has changed for the better. People aren't walking away anymore, putting their hand over their nose or checking their baby's diaper (yes, that happened! ). I'm so much more confident!
For bad breath, I take a level desertspoon of diatamaceous earth once per day in a drink, works a treat