Brief Answer: you may have sinus infection! Detailed Answer: Hello There can be 2 possibilities in your case First one is that because of the cold, your smell receptors in the nose have been damaged and this is causing the bad smell! , dont worry, this is a reversible phenomenon and you will recover in a week or two. Second possibility ( which is more likely) is that , because of the cold , you may have developed a sinus infection and this is causing the bad smell, nothing to worry here also as most of these infections are easily treatable with antibiotics and nasal decongestant drops. Please meet your ent doctor for examination, to confirm this , he will prescribe you the necessary drugs! Meanwhile you can start steam inhalation 5-6 times a day! Regards

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