do you still live in the same house you smoked in? if so, get an air purifier or look online for machines you can rent to rid your house of cigarette smoke, odors, etc...also, find supplements that heal your lungs, go outside and do deep breathing excercises...get out and walk! yes it will take time, but if it persists and goes on and on, see your doctor!
How long has it been since you quit? And, "Congrats!" That is awesome! :) Depending on how long (years) & how much (per day) you were smoking, it could take a reeeaally long time for your lungs to completely "clear out," and heal up. It's possible you will always have a some level of cough. If you smoked a long time, your lungs are likely quite damaged. Don't let that discourage you -- you've overcome a VERY tough addiction & significantly reduced your risk of lung & heart problems & diseases. Exercise -- especially anything cardio -- can help your lungs clean/clear up a lot. Try running, or walking (as fast as you're able), at least 20 minutes per day. Doing anything that increases your heart rate & respiration will help your lungs & heart to become healthier! If the cough is annoying you, try some cough drops or sugar-free hard candies. And, again -- Congratulations!! :)