I feel a sharp pain in my heart , it comes suddenly often , or after playing some sports , so what did you think is that?

Nothing vs ER: Could be nothing more than ligaments and muscle stretching, statistically in your age group, most common and non-life threatening. However, the riskier side is dramatic ie sudden death due to a heart abnormality. See your sports medicine doctor or sports medicine cardiologist (heart doctor). Asap! and refrain from activity that brings the pain on.