hello angieboo,
Realising your symptoms are anxiety driven is a great place to begin building on your confidence, and hopefully you will be able to knock back the panicky feelings. I do know it is easier said than done, but it can be done, and you must trust the rational side of your thought process to take charge. One thing which has helped me in the past when I have felt a wave of panic beginning to rise, is to say this can go one way or the other, the decision is mine - take control and turn your back on the negative thoughts.
It is great you have made the decision to quit smoking. I know several people who have stopped, and they also developed a cough to begin with - strange why that should be. At least your chest infection has been treated, so I am sure you will be feeling fully recovered soon.
Hope you will be feeling less anxious soon