Long coughs.... Cannot stop.?

I have this cough that's lasted for about 3 weeks now. I have no fever just phlegm (lots of it). Recently I started to have a running nose, but not until 3 days ago. And when i breath in it is fine, but sometimes tickles (thus causing me to cough) and unless i breath in all the way with my diaphragm filled, then it sounds a little like a soft soft whistle (only at the very last moment in the inhalation). When i breath out it is completely fine, but just the very last moment in the exhalation it creates this nasty gasping sound.... I have no clue whether it is a viral or bacterial infection. I'm afraid the doctor would give me the wrong diagnosis and end up taking antibiotics for a virus. I have never had this happened to me before, im actually kinda scared (the sound made when full inhalation and exhalation ...). Please let me know if you have some guidance.