Sorry to hear that you are feeling bad. Breath odour has many causes - a quick search online indicates the following:
"Bad breath related to poor oral hygiene is most common and caused by release of sulphur compounds by bacteria in the mouth.
A fruity odor to the breath occurs as the body attempts to get rid of excess acetone through the breathing. This is a sign of ketoacidosis, which may occur in diabetes. It is a potentially life-threatening condition.
Breath that smells like feces can occur with prolonged vomiting, especially when there is a bowel obstruction. It may also occur temporarily if a person has a tube placed through the nose or mouth to the stomach to drain the stomach contents (nasogastric tube) in place.
The breath may have an ammonia-like odor (also described as urine-like or "fishy") in people with chronic kidney failure."
You can help your GP by looking for patterns - possible related to how soon after you eat do you smell this and perhaps what you eat. Sulphur compounds etc etc from the oral area can also be perceived as fecal so you need to make sure you carry out proper oral care each day - floss, brush etc.
You might want to get a second opinion and try to be as articulate as possible. Hope you feel better.
I'm looking more into permeable colon wall or Intestinal Permeability. I didn't write about breath.... It's a smell i get one could say out of nowhere. I feel really tired, fatigued and i get episodes of hives. Along with abnormal body odor. I'm sure it's not incontinence because my butt hole never leaks. So it must be something different.. the only thing that makes sense to me right now is intestinal permeability.
Guess wut im trying? Apple cider vinegar :p
I share your problem and would be glad to hear if apple cider vinegar did help.