I have been going thru the same thing with this fecal smelling breath. I have tried everything on the market from smartmouth, therabreath, scrapping my tongue, brushing after every meal. Still had this foul smell. I went to dentist and I had no cavities. Had an egd and colonoscopy done, result had acid reflux. Started talking acid reflux meds and still no help with the bad breath. I still had this white coating on back of my tongue. what was the last straw for me was one day at work the air vent was blowing directly over my head and the women behind me was covering there nose. Saying what is that smell. I was so embrassed I pretend I was sick to leave work. I tried the probiotic and it didn't work. So I called and made an appointment with another gasterologist. I talked with her and asked the doctor if I was not having a regular bowel movement and had acid reflux and the medication was not working will it cause bad breath, she replied yes. I explained to her that my mother, sister and neice had grastroparesis. So she test me for it and that what my problem was my stomach was not empting or digesting my food and it would just sit in my stomach and sour and the smell would come up thru my esophagus and out mouth. So put me on a stronger acid reflux medication dexilant60 mg and something for my chronic constipation amitiza 8 mcg. And told gave me the gastroparesis diet to eat 6 smaller meals. No red meat, no vegetables, milk, cheese and now oatmeal or whole grain. so for breakfast I would eat 3 peanut butter nabs and drink 2 glasses of water and for lunch I would eat mash potatoes or baked potatoe or just and no meats for the first week. I didn't hear any laughing and co workers passing by asking what is that smell. I thought the bad breath came from your mouth not your stomach or from being constipated. So if you are having fecal smelling breath go see a gastrologist to see if you have acid reflux, gastroparesis or if you are constipated. Some people may not have the bad breath if they have these symptom but I did. Now I don't have the white coating on the back of my tongue anymore. Maybe this information will help you.