48 yr old healthy male, takes no meds, has no allergies or sinus issues, suffering from halitosis. what could be the cause?

Bad breath: Bad breath (sometimes referred to as halitosis, fetor oris, or fetor ex ore) is defined as any detectable offensive smell carried on the breath. It is largely the result of bacterial breakdown of certain Amino Acids derived from proteins and glycoproteins present in stagnant saliva, food debris, desquamating epithelial cells, blood, and postnasal drip in the oral cavity.

See your dentist.: The most common cause of bad breath is the health of your gums and teeth. If you have gum disease ( which would not necessarily cause you pain) or cavities you could experience bad breath. These conditions are caused by bacteria. These bacteria produce by-products in your mouth that smell terrible. A dentist should be seen to rule out the obvious causes.