Random sharp chest pain on the left side & ive had pneumothorax 2 years ago, help?

[Yaray Lizama]

im 15 years old, 5'7, 164lbs. healthy. no stress or anxiety. nothing Like that. dont smoke nor drink. had pneumothorax 2 years ago, they said they have no idea why it happened., been having a lot of random sharp chest pain on my Left side near my heart & lung. Any ideas on what it could be?
im a Girl!