I have had an absolutely hacking cough for the last 2/3 months. It all started out with what I assumed to be a sinus infection (post-nasal drip, awful pain in forehead between and above the eyebrows, runny nose etc) and I was put on a course of Doxycycline to ease it. The pain went away but the runny nose and post-nasal drip did not. I also developed an awful, awful cough that produces thick, greeny/rusty coloured mucus. The cough is usually at its worst right after I wake up. I have also found that I have been getting headaches far more often (mainly on the left side) and I constantly feel run down. I've lost my appetite almost completely very recently too. I find myself running out of breath having just climbed up a small set of stairs and have been getting pains in my ribcage on the right side of my chest which makes it very difficult for me to breathe. I am usually very healthy, but I do however smoke about 5-10 cigarettes a day, which I understand is awful for an 18 year old girl. I've been to see the dr. 4 times now and no amounts of antibiotics have helped me and a chest x-ray came back clear so I really have no idea of what I should do now since this is making my life very, very difficult at the moment.