I have dry fish like odor inside nose. I can feel it only when I do nasal rinse and move my head with solution inside and when it is coming out. I have thick sticky mucus and post nasal drip for which I consulted multiple ENTs but they said everything is fine checked both ct scan and endoscope. But when I did nasal rinse with salt+baking soda+xylitol old green thick  mucus came out. Now only colorless or white mucus but odor is there. This odor is causing halitosis as well. Is it biofilm do I need antibiotics? I have no other health issues only vit d is low (20.6 ng/mL).