How do I help my son from this point on? Do I try help him in my home or try to find out of home place to treat him?
The first thing you have to figure out is: What do you want to help him with.
Does he use drugs or is he just going through a period of independence, which is normal for all adolescents. How old is he for a start?
If you want to find out whether he uses drugs without using a drug test which they can fool, then:
a) Take time off from your work (14 days)
b) Rent a cabin in a remote area
c) Go there with your son. Get some family member to dump your off so there is no car to steal. Arrange for supplies to be brought, so you are cut of the world.
d) Observe and talk with your son. If he is using drugs he will start a detox period in days and show signs of discomfort. He will alter his behavior. If he does not, then there is nothing wrong with him. Then he is going through a phase and you can return to society with the knowledge that you will have your old son back again, when he has passed the phase.
It is basicly the same the wilderness therapy does. It just cost a lot more.
However, sometime wilderness therapy can fix the phase issue also by scaring your child to disobedience. He would have to bring the process about growning into an adult to a stop until he is 18 and does not have to be scared from you anymore. If you choose that option, be prepared for an increase version of all those problems you face now, when he tries to catch up with his development at that time.
You can fix it on your own! But you have to put time and effort into it.
Being a parent I understand how difficult it is to remain listening when the child says something you know that is not right. But it is important to hear the child out before you bring your own arguments on.