Sinus infections often start with a cold or allergies and then evolve into a sinus infection. If it's been more than two weeks and you are suddenly experiencing facial pressure, headaches, a discolored brown-gray-yellow nasal discharge, there's a good chance you may have a sinus infection. To learn more about sinus infections, how to detect them, prevent them and how to treat them, click here to read Dr. Timothy Knudsen's blog.