I have trouble breathing through my nose, I am constantly swallowing mucus and get mild headaches.?

For the last several years I have noticed difficulty breathing through my nose and have been a "mouth breather". Also, everytime I swallow, I swallow a lot of mucus. For the last week I have had a dull headache behind my right eye. Could there be something wrong with my sinuses? My nose is not running but when I wake up in the morning I have dried green "boogers" in my nose. I took Sudafed last night and it helped but I don't know if it was because of the pain relievers or because it opened my sinuses.