Hello, Thanks for posting the query. There could be several reasons for bad smell in the nose and breath. It could be due to poor oral hygiene. A second reason is a non-allergic, non-infectious inflammation in the sinuses that can linger after a cold. A third reason is chronic sinusitis. In your case, it looks like you have developed sinusitis after cold. Inflammation in the sinuses can block sinus drainage. This can cause the mucus to collect in your nose and sinuses. Over time this collection of mucus can smell really bad. If the mucus is thick, a nasal wash may be needed to remove it from your nose and sinuses. Steam inhalation will help you. Do maintain good oral hygiene. You may have short-term relief from the bad smell, but it may return again if the blockage is not completely cleared. If this continues, check with your doctor to see if a decongestant like Sudafed (pseudoephedrine) would clear this blockage so the mucus drains from your sinuses. Your doctor may also recommend a prescription of nasal steroid spray. This decreases the inflammation in your nose and sinus and the mucus production. Generally a nasal steroid spray keeps your sinuses draining better. This may prevent the mucus from collecting in your nose and sinuses. To get the most help from a nasal steroid spray use it after doing a nasal wash. I hope I have answered your query. I will be available if you have any follow up query. Wishing you a fast recovery. Regards, Dr. Jyoti Patil.