Tooth extraction = sinus infection?

I had my upper left molar extracted roughly 2 1/2 weeks ago. I ended up getting dry socket, in which the dentist did pack it, and it felt great. The days go by and my tooth, or lack-there-of is feeling really good, but my nose keeps getting plugged up or it starts to run, in which it has been doing since about day 3. The fluid smells and tastes bad. As of today, the good news is my tooth area feels almost 100 percent, but what is with the plugged/runny nose?. Could I have a sinus infection, and if so, how is it treated? Thanks