Hello i had gone through your question diligently and I can understand your concern I am listing here the common causes of bad smell in nose a lump (polyp) in nostrils sinus disorder foreign body in nasal cavity Bad breath may occur in various disorders of food pipe and stomach ,throat and lungs or dental problem like peroodontal diseases I would like further information to guide you better 1Do you smoke 2 do you have any family history of diabetes or sinus problem 3 have you ever been exposed to occupational carcinogens You should worried but not so much until diagnosis confirmed please make a visit to ENT surgeon for thorough clinical examination and a sniff test (breath test) if it comes inconclusive see a dentist for dental check up meanwhile, maintain good hygiene have a healthy diet gargling with antiseptic solution I Hope you will find my response helpful and informative please feel free to our ask for follow up questions wishing you good health Regards