My Son Was Playing Lacrosse And The End Of His

My son was playing lacrosse and the end of his stick jabbed into his stomach between his ribs (diaphragm area) and knocked the wind out of him for a few seconds. He is still saying it hurts when he breathes in deeply. He was able to eat , talk, etc and there is not even a red mark. But I am concerned could he have punctured any thing? should I take him to the ER?