Gum disease is caused by tarter build up and the number one symptom of tarter build up (besides tarter of course) is bad breath. Brushing doesn't help and the only thing that helps is the dentist removing the plaque and tarter. He could have a tarter problem or gum disease. If he is on any medications, it could be a side-effect of those as well. I would speak with a doctor or dentist.
sinus infections can be the culprit.
I am 30 years old, and I HAVE This moth ball breath thing. How do I know? Everytime I get close to someone they offer me a mint or gum - EVERY TIME. I have had people tell me also. I have had people look like they were going to newly throw up when sitting across from me eating. Also, I had a man, that I used to work with, and it used to almost ball me over. So I know exactly how bad this is! If I use a very strong mouth wash - it actually makes it WORSE! So bad, that if I breath heavily, I can actually smell it MYSELF if I breath hard. Now you know that is bad, when you can smell it yourself. The good news is, I know what it is. It is gum disease. I have stage 2 Gingivities/ its a periodontal disease. All of those words are probably spelt wrong, but you are smart...and can figure out what I mean. Anyways...I would suggest going to a great dentist - and have their gums rooted, and scaled - they grade the gums. If the gums have "pockets" they call them - the smell gets trapped in them. I know its gross.
My 67 year old husband also recently began taking cholesterol and blood pressure medicine (Lipitor & Altace) and I have noticed the "moth ball" breath syndrome. Sounds like a clue to me.
My 43 yr old husband recently began taking cholesterol and blood pressure medicine, and shortly afterwards, I noticed his breath smelled of moth balls. He has had no other complaints or symptoms and plans to consult with the doctor about it during his next visit. We don't know if it's related to his medication, but that was the only change he had made.
It has been my experience that "moth ball" breath is an indicator of tooth decay, even if there is no pain. You might want to visit your dentist.