Foul smell from mouth. Of this disease.

Respected Sir/ Madam,  I am Sandeep Sarkar, 26 yrs old, student. I am having a "Bad Breath" from mouth and which is a strong foul smell smilar to human poop smell.  No matter how many times I brush my teeth, and use tongue cleaner/scrapper, it will surely smell bad. I can feel the foul smell coming from inside not from the mouth itself; or maybe from both i.e., mouth and through food pipe or due to Esophagus.  My mouth always get dry and conditions become more worse.  To talk with someone it has become a nightmare. The foul smell is so intense that even I can tolerate it's odor/smell. It's happening for the past 6 years. I am currently taking Himalaya Liv 52 DS for Liver, because it could be link. Please, I request to all the Doctors that please help me get out of this disease. Thank you