Hi,
How are you? Do you still experience the sharp pains in your chest? Aside from heart problem, this could indeed be due to non-cardiac causes such as pulmonary, musculoskeletal and even gastrointestinal in nature. this is more likely costochondritis, which is very common in young people. if it persists, you may need to have this evaluated further by your doctor. Take care and do keep us posted.
Sharp pain is rarely a symptom of a heart problem, especially in the young. More than likely it is muscle or cartilage problem.