I have had a really bad cough for over a month now. It started with a sore, dry throat , but quickly progressed. I have been coughing up green phlegm a lot and it is hard for me to breathe when I sleep sometimes, and even during the day. I have been feeling very fatigued and my nose feels very plugged, but I can breathe fine through it. I know this is not just a cold, because this has never happened before. Any ideas of what it could be?