Having a persistent cough... Help?

Hi, I am 20 year old and I am a regular smoker. I am having this persistent cough for the last 3 days. It started a week ago and it seemed normal because it was accompanied with phlegm. But now the phlegm is gone but still the dry cough is there. It becomes worse at night and I can't sleep. And when I breath it feels like something is stuck in my windpipe. What can it be? I quit smoking because I am very scared... Plz help