Hello~I would try taking the mineral supplement Zinc, sometimes this can help with bodily odors. Also, add a good, high potency pro-biotic to your diet, this will put the friendly bacteria in your system and may very well stop the foul odor as well.
Hey albertony.
It's likely because of the presence of anaerobic bacteria, who love that moist and warm mucous environment.
My suggestion is to use a saline solution 3-4 times daily
with the help of a neti pot, combined with once a day
(1st thing in the morning) "oil pulling" with one tablespoon of virgin organic coconut oil.
Doing conscious nasal breathing exercises will also help.
Look into Pranayama breathing exercises.
Best wishes,
Niko