Hi,

Before even reaching to conclusion of seeing a doctor, try to list out the things which suggest you to see a doctor and if you are seeing some unusual behavior pattern, try to find out the timelines etc and at least you will be able to figure out the events and incidents happen making him do something unusual... again these are just some things even the doctor will be asking.

But the best therapy is the close bonded relationship of a child with mother regardless if unusual behavior occur from birth or recently.
You can PM me, shall be glad to assist as much I can.

Take Care & God Bless