1) not having the tongue clean
2) not having a dental cleaning
3) having an uncontrolled bone loss
4) a recurrent tooth cavity
5) a gastro intestinal condition undiagnosed
multiple cavities may also lead to bad breath. If it's not an oral issue, it may be stemming from your stomach. Before conducting medical tests, though, I would make an appointment with your dentist to evaluate your periodontal condition by conducting a thorough medical history, a complete periodontal exam, a cavity check and take current X-rays if you haven't had them for awhile. By doing so, the dentist can conclude if in fact the bad breath is stemming from an oral issue or you need to be referred to a specialist for further work up. Good luck.