What Causes Headaches, Cough And Loss Of Appetite?

I have had headaches almost daily for a couple of months. Along with these headaches there is clear runny nose, not helped by blowing my nose. I also experience postnasal drip with a constant cough, nausea, and loss of appetite. I tried Sudefed otc, alkaseltzer cold and sinus and Fluticasone. Still have symptoms