I am experiencing the exact same problems. For about 8 years now. I just went to the dentist a month ago. Nothing there is causing it. My dentist said there are three things that causes bad breath. Gums, nasal or stomach. The ent found nothing. Actually I have been to several ent doctors. Also several dentist. I’ve had several CT scans with contrast. They found nothing. I recently visits doctor who ordered blood test for amalayse. (I hope I spelled it correctly) It’s an enzyme that is made by both the pancreas and salivary glands. There is something about my saliva that I just can’t seem to figure out. It seems this is where the problem is. After finding out about the elevated enzyme she ordered an ultrasound of my abdomen. The results showed a dialated pancreatic duct in the distal portion. And a fatty liver. The doctor said it comes from eating too many carbs. My body does not seem to digest carbs and sugar. I am waiting on a CT scan . My insurance company denied it. So my PCP is sending me to a Gastroenterologist. Hopefully they will approve it. From what I have read on google. A dilated duct could be a tumor. Also high risk for cancer. When the duct is blocked the digestive enzymes are not released. I have always said my food is not digesting properly because can smell everything eat. My poop smells very bad. The smell is also coming through my nose. I know for sure it is in my nose and throat. My breath can fill up a room. It has a fecal/sour smell. I’m not sure if it is coming from my body. I have heard vitamin b2 may help. It is Riboflavin. I will keep everyone posted. I will have a phone conference on April 23 due to coronavirus. I hope to have the scan as soon as all this is over. My doctor just got my results from the sibo test. I hope to get those this week. Good luck.