I am having the same thing, right now. I am 68 years old and in general good health. I now have a
cold that produces a lot of yellow mucus on on the left side. When I blow it out it smells like
excrement! I was going around the house for several days and every time I blew my nose I thought oh
my goodness, the cat must have pooped in this area, until I finally connected the smell to blowing
my nose. The more yellow mucus the worse the smell. I did have a flu shot last month, and this is
otherwise a very mild cold, so I'm not going to worry too much about it, just let you people know
you are not alone.
I had polyps surgically removed from my nasal passages twice, once in 1988, again in 2010. Both
times it made a dramatic improvement in my breathing ability, and I have not lost my sense of smell,
which is listed as a possible negative side effect of such surgery. I have never smoked in my life.
Even with this mucus producing cold, neither nasal passage is blocked, I am breathing freely.