Hi.. Thanks for the query.. I have gone through your query and can understand your concerns.. As per your complain it seems that altered sense of taste and smell along with smoky taste at the back of nasal passages that started with cold seems to be due to sinus infection or sinusitis.. As the sinuses drains through nostrils therefore there can be bad smell through nostrils and post nasal drip can cause bad taste if the mucous is infected.. I would suggest you to consult an Otolaryngologist and get evaluated and a thorough clinical evaluation and investigations like PNS view x ray or MRI scan can help in diagnosis and treatment can be done accordingly.. You can be advised a course of antibiotics, anti-inflammatory painkiller like Ibuprofen, decongestants like Pseudoephadrine, do saline nasal irrigation, steam inhalation and use a humidifier in your room.. You can also be advised decongestant nasal sprays containing Xylometazoline or Oxymetazoline.. Avoid spicy and chilled foods.. Do warm compresses around nostrils.. Hope this information helps..