Your Son was born under a Gandmool Nakshatra by the name of Revati, I do hope that you must have done the Gandmool puja at the time of his birth. Presnetly he is running the Vimshottari dasha of Ketu and Mercury which are not placed well in his chart. You can do remedies of Ketu.
1. He should wear Moti on his right hand ring finger