How To Treat Flu Leading To Chronic Cough,fever And Headache?

Hi,My name is Jeanie and I am 54 years old. I have had the flu for two weeks now.Started with body aches , headache, fever and fatigue. A few dates later a cough started. Started with a dry cough and has turned into a cough that is more productive and I can feel rattling with I breathe and have some shortness of breath. A few days ago I thought that I was feeling better but now cough is so much worse. I gave never experienced thus horrible of a flu before.My question is should I let the virus run it's course or see a Doctor?