Bad breath. Any hospital to recommend?

I have bad breath for many years and I have been to several hospitals but the doctors said I don't have that much strong smell and they don't do good check up. I have gone through many medications and I am still suffering from this disorder. When I said I have bad breath, they just look inside my mouth and say there's nothing wrong but a little cavities. Whatever I have done was just a waste of money and time, I am hoping to see a good doctor and get a through checkup and get well soon, I am thinking that the bad breath might be symptoms of liver or kidney disorder, so it really is a serious problem. What have years of experienced doctors have to say about it? What is best to do? Do you have any hospital to recommend? Thank you