It doesn't sound as if it is clearly a sinus infection. My ears clog and pop all the time now that I am in the UK when I am sick, but I have never had a sinus infection. And it drives me insane. It only happened once in the U.S., at boot camp, otherwise known as the sickest place on earth.
Have you had sinus infections before? Often people have recurring sinus infections throughout life because they naturally have bad drainage. As expat said, if you do start getting them, regular irrigation is key.
Apparently, they have moved away from the green/yellow mucus is a sign of infection. But smelly mucus, still bad.
You really need to try some decongestants and see if that has an affect. Generally, regular colds will respond to decongestants, sinus infections will not.
It is hard to tell the difference between the two, there is no real test, but most doctors recommend seeing someone if there is no change after 1-2 weeks.
Since it is mainly guessing whether it is an infection, prescribing antibiotics can do more harm than good with causing resistant bacteria.
http://oncampus.richmond.edu/student_health/ailments/sinus.html