After not smoking for several days, why do my lungs hurt badly?

Breathing real air: Congratulations on doing the most important thing that smokers can do for their health! you stopped smoking! i do not hear this complaint often. It might be due to an infection that happened after you quit smoking. If you have a fever or productive cough or wheeze, see your doctor. If not, i'd attribute it to your body's need for the nicotine. I'd also think about nicotine replacement to help.

Many possibilities: Hard to say for sure but the lungs often start to produce a lot of phlegm because the cilia cells are no longer paralyzed from the tobacco products...So one can get a mild bronchitis. Standard care for bronchitis might help. It'll likely get better soon. Drink plenty of fluids. Good job and keep at it!