I used to have bad breath, especially when i flossed, I could smell it pretty badly. sometimes it was a fecal smell.
What worked for me was flossing twice a day and the key factor was swishing water diluted in clove oil. salt or oil pulling didnt do it. it was the clove oil.
it completely went away after that. that's a pretty cheap experiment but not sure if that's your cause.
bad breath could also be due to dental infection or congested liver - have you tried Liver Flushing before?