Hello,
This must be such a worry for you and so hard not to know how to support your son.
If you would like to talk with someone who would understand please contact us at The Icarus Trust.
We are a charity that offers support to the families of those struggling with addiction. One of our trained and experienced people would talk with you if you get in touch. This might help you to know how to go forward and to find out what other help is available.
You can contact us on help@icarustrust.org or visit the website http://www.icarustrust.org
I hope this helps.
Good luck.