Hi.. Thanks for the query.. As per your complain bad smell/ taste in mouth even after brushing, flossing and mouthwash can occur due to a number of causes and the most common reasons can be tooth and gum infection.. If you have a decayed tooth then it can be a cause for continuous rotten taste and bad smell in mouth.. Poor oral hygiene and sinus infection can also be a cause.. In case if you feel that it is coming from the throat then post nasal drip, tonsil stones and acid reflux can be a cause.. I would suggest you to consult an Oral Physician and get evaluated and a thorough clinical examination and investigations as per suspected cause like x rays of decayed teeth, PNS view x ray of sinuses etc can help.. As of now you should chew flavoured sugar free chewing gums and also do warm saline gargles.. Limit intake of high aroma foods like onion and garlic.. Do steam inhalation with few drops or Eucalyptus oil in boiling water.. Hope this helps.. Thanks and regards..