I am suffering from very bad mouth smell from last 3 years. I am drinking 5-6 litres of water but it helps a little. I consulted dentist and he says its not mouth problem just drink more water. But situation is not improving. Constipation and sometimes black stool comes. I consultation a physician and he says no problem just eat more fruits and drink water. The situation of smell is worsening and it persists 24*7.what should I do?