I know how you feel, i had the same thing happen to me, and it is a scary feeling. The good news is it will go away, and may come back again, mine came and went a few times, but it has been quite a few weeks now and it has stayed away, and i am feeling much better now. It is just part of how your body starts healing, although i know it doesn't feel like healing.
Don't worry about the phlem.... it will come up when it's ready, drink tons of water, it is good for your lungs also. Try to relax, and breathe slowly, in a day or two you should start feeling better.
Good Luck,
congratulations on your quit!!!
Emily