Hello!
What a worry! But I can imagine how I woud feel if a child came into my hitherto quiet and peaceful environment and ran amok!!
Your little male is showing all the natural sign of being young and playful and only time will calm him down. In the meantime, make sure there's somewhere quiet and comfortable where the older cat can hide - and give her lots of TLC. Whisper to her, too! It's amazing how therapeutic a quiet voice can be to any animal, especially a cat....or am I preaching to the converted?!! :o)