<s>[INST] I have this constant bad taste in my mouth and on my tongue. No matter how many times I brush and floss my teeth it never goes away and causes bad breath. Ive been to my regular doctor and had a complete physical with blood work eveything came back normal, she said it could be acid reflux and put me on a prescription which did nothing she then sent me to an ENT Specialist all tests came back normal she then sent me to a Gastroenterologist in which i had an endoscopy done and that test came back normal as well. The foul taste and odor in my mouth is getting worse. Im at a loss of what to do. [/INST] Hello and Welcome to Chat Doctor, Thanks for writing to us. Respiratory problems, bacterial infections, gum, dental and other oral problems, as well as certain types of diseases, Chat Doctor.  If the bitter taste persists throughout the day, it could also mean that you might have a liver problem. Therefore, a proper prognosis and treatment in such cases is vital to avoid affecting your day-to-day activities. If the bad taste in your mouth that is accompanied by other symptoms such as sore teeth, sores in the mouth, ulcers, stomach problems or any other growths in the mouth you should see a physician to ensure that there is no more serious causes to the bad taste you are experiencing. Hope this helps you. Wishing you good health... Regards. </s>