When it comes to bad breath, most know to avoid the repeat offenders such as strong-smelling foods or tooth decay. But your bad breath might not be coming from the condition of your mouth, but your stomach. In fact, bad breath from stomach issues can be even more perplexing than typical bad breath, because it's harder to identify, isolate and treat. Still, understanding the different causes of stomach-related halitosis can help you decide if your bad breath is just from a garlicky lunch, or something more serious.