I remember in one of your earlier threads you said you smoked about 7 grams a week, right? For a young woman, that's a good bit of smoke inhalation, tar, resin, and other particulates.

Makes sense to me that your lungs are simply irritated and you're coughing up that nasty crap that everyone inhales along with the good stuff, the active compounds. Give yourself a smoke break. And if you're really worried, go see your doc and let her/him listen to your chest and give you a chest X-ray if it's deemed necessary. Lungs are mighty valuable organs to take a chance on.