Update?
There are many diseases that lead to bad breath and body odor, among them cancer. A little compassion and empathy would go a long way.
Major culprit of bad breath, where dental hygiene is met and loss of sense of smell has occurred, are the sinus. Among the diseases affecting sinus are
1. Sinusitis (with constant post nasal drip)
2. Rhinitis (There are several versions of this disease)
3. Diphtheria
4. Tuberculosis of nasal mucosa
5. TMAU