The most common cause of bad breath is poor oral hygiene. Bacteria that build up on a person s teeth, tongue and gums can cause plaque (the soft, white deposit that forms on the teeth s surface), gum disease and tooth decay.Eating strongly flavoured foods – such as garlic, onions and spices – is likely to make your breath smell.Some types of medication can also cause bad breath. Is he on any medicines ? Dry mouth, also known as xerostomia, affects the flow of saliva. A lack of saliva can cause bacteria to build up in the mouth, leading to bad breath.In some cases, gastrointestinal conditions may cause bad breath. For example, H. pylori infections (bacterial infections of the stomach lining and small intestine) and gastro-oesophageal reflux disease (GORD) have been linked with bad breath. I have briefed the few conditions causing bad breath. TO your doubt if he is diabetic, I would ask if there is any family history of diabetes and of course check his FBS, 2 Hr PPBS and HbA1C and decide. Intense thirst,appetite and frequent urination can make one think of diabetes.For seizure as you said, an EEG will be useful and your doctor will ask . Please get back to me with more doubts.Regards