From what you briefly described, it sounds a lot like the early stages of emphysima. But because of the fact that you said you rarely smoked ciggaretes and only smoked up for five months, it would be pretty d@mn rare for you to be diagnosed with that.

I would have to agree that you could just be feeling anxiety from quitting. It is most likely more that your stressing over it and making it worse because quitting something no matter what it is isn't easy by the way. My advice would be to relax, drink a bunch of water, and see a doc. Stay strong and good luck bro.