Hello Grace,
Welcome to Healing Well.
The lower respiratory system includes the bronchial tubes and lungs. Respiratory problems are less common in the lower respiratory system than upper respiratory system. If your having pain you may need a bronchoscopy.
Due to your age I would like to suggest you talk with your parents about getting a medical screening exam to see if you have a problem with your lower respiratory system.
Just my personal opinion.
Take care
Kitt