I had the same problem too! My doctor gave me xyzal and I did the nasal rinse while on the medication......after a few days I didnt have the smell from my nose anymore!
have had the same bad smell\taste in the mouth for over 6 months now. Couldn't figure out what the hell the problem was. Mine became so awful that the smell would literally funk up my entire office at work. I too was convinced that the smell was coming from my nose. Because of this, i ended up at an ENT, who convinced me I needed surgery on my sinuses & tonsils. Well, after having tonsils\adenoids removed, upper gi, lower colon splenoid or something done, and all kinds of other medical test ran. The culprit turned out to be a crown on the lower left molar tooth. The tooth up under the crown had split in half, and the damn thing became infected or something. When the smell first started, the first place I went was to the dentist (of course they didn't see anything wrong). I ended up on a wild goose chase that cost me thousands of dollars. Finally after reading another site and listening to the guy on there story, I went back to the dentist and lied that the tooth was bothering me. That's when the dentist decided to take the crown off (he couldn't tell anything from the X-ray; the crown was n the way of seeing my actual tooth). He ended up having to pull the split tooth. He told me to come back for a bridge of something once it has healed but "No Thanks!" I'll leave the spot empty because empty doesn't become infected and stink up a whole room......
Most halitosis come fron dental origin. Once you have your tooth fixed, probably halitosis will go away.