Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain it seems like you are suffering from sinus infection leading to the symptoms of foul odor in nose especially on bending, headache and bad taste can be due to post nasal drip.. There can be infection and inflammation in the sinus or thee can also be a polyp formation and it can be confirmed only after a thorough clinical evaluation and investigations like PNS view or MRI of sinuses.. You need to consult an Otolaryngologist and get evaluated.. In case of Sinusitis caused secondary to infection he can advise you to take antibiotics like Augmentin or Clindamycin, Anti-inflammatory painkiller like Ibuprofen or Naproxen, decongestant like Pseudoephadrine and doing steam inhalation and using a humidifier in your room.. You can also be advised to do saline nasal irrigation and take steroid nasal spray.. Doing mouthwash gargles and taking steam with a few drops of eucalyptus oil in water can help in masking bad smell.. In case of polyps in sinuses or thick mucous that does not drain with medicines surgical removal can be planned.. Hope this information helps. Thanks and regards. Dr.Honey Nandwani Arora.