Is this normal for tennis players? I’m worried about my dad

My dad, 51 and 60Ibs overweight, plays in some indoor tennis leagues 3 times a week. Yesterday he apparently fainted playing tennis and when he became conscious again he had no control over his left arm. He can move and use it now but still. I was only told about this a few minutes ago because he didn’t want me worried before my math exam this morning. Even though my dad didn’t want to, my mom made him go to the ER and that’s where he is right now.