Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain it seems that the foul smell in nose that goes away with decongestants as well as there is also a history of recent tooth extraction reveals that there is a high probablity that there has been perforation of the floor of sinus when the tooth was extracted and it has led to progression of infection in the maxillary sinus.. Although at times the healing takes place and there is no formation of an oro antral fistula but the sinus might get infected.. As the sinuses drains through nose, you are experiencing a soul smell in nose.. I would suggest you to consult an ENT expert and he can advise a PNS view x ray of sinuses or MRI scan to look for the exact cause of the smell and treat accordingly.. In case of sinus infection, you can be advised to take a course of antibiotics like Augmentin, anti inflammatory painkiller like Ibuprofen,decongestants like Phenylephrine as well as nasal decongestant spray containing Xylometazoline.. Saline nasal irrigation and steam inhalation can also be helpful.. Hope this information helps.. Thanks and regards. Dr.Honey Nandwani Arora.