What Causes Throat Irritation Upon Smoking While Trying To Quit?

I am trying to quit smoking. I have a history of panic disorder but haven't had a panic attack since may. I've been smoking on and off for 2 years now. I am hoping that the feeling that I am not getting enough air is not because of this because I really do not wan to have another panic attack. I have been exercising and cutting down on my cigarettes. 50 push ups and sit ups. Then I run for about 10 min. And I'm only smoking 3 - 6 a day. So about a pack a week. What's bothering me though is that my throat gets really irritated when I smoke now.