I have sinus pressure around my eyes and nose. Every once in awhile a yellow colored, smelly liquid runs from my nose. Could it be a sinus infection?

Yes. This may be a sinus infection, viral or bacterial. If it is only several days, it is likely viral. If it has been longer than 7 days, then it is likely bacterial. Sometimes your body is able to fight off the infection and you can help yourself with otc decongestants, afrin nasal spray (5 days total), saline nasal spray or netipot, mucinex, (guaifenesin) and hydration. If not better you will need to see you d.
Sinus Drainage. Colored sinus and nasal drainage means plugged up sinus passages. If this pressure and drainage has been going on for longer than ten days, yes, you have a sinus infection. Try an oral decongestant. If you don't get better, go see your doctor.