One frustrating thing is that everyone's quit is different. Some people adjust very quickly, both physically and mentally, to life as a non-smoker but most people take a while, especially if they smoked for a long time.
After my first couple of months, I was feeling a lot better but around my 7th or 8th month, I was hit with prolonged periods of anxiety, depression, and renewed thoughts of smoking. It was very frustrating for me as I felt I was doing so well but I fought through it, did NOT smoke, and eventually things got better.
Everyone's quit it different so there isn't a magical date in your quit where everyone feels better. The best thing you can do is just fight through this. I know that probably isn't the answer you wanted to hear. But it does get better with time
Regarding your chest issues, I agree with Doreen.