This sounds like an upper respiratory infection that could involve your nose, throat, sinuses and/or your larynx. It could be from a virus, of a type that can also cause flu-like symptoms. If caused by a virus, symptoms may worsen and improve, but should definitely start to resolve at this, the ten day mark. More worrisome is that it could be a 'strep throat' or, as you suggest, also involve your lungs. Still sick after ten days, you should be examined, have a strep throat culture and, with the feelings of chest heaviness and congestion, a chest X-ray. You may need antibiotic therapy for upper respiratory infection, lower respiratory infection or both.