4Postnasal Drip
A bad smell in the nose, particularly when it is thick and drip constantly down the back of the throat, can be an indication of postnasal drip. In general, mucus plays many important roles, such as responding to infections, keeping the nasal membranes healthy, filtering foreign particles from the airways, and humidifying the air. Sinus infection, allergy, flu, or cold may thicken mucus, making it more difficult for it to drain properly. In mild cases, postnasal drip might not affect your breathing or cause a bad smell. But if wheezing happens and the smell becomes worse, visit a doctor immediately. [5]
