The first place to start is with a comprehensive assessment by an Addiction Psychiatrist, American Society of Addiction Medicine (ASAM) certified addiction professional, or a licensed mental health or counselor with clinical experience working with substance use disorders. The assessment will include demographic information, substance use history, other mental and physical health problems, use of over-the-counter and prescribed medications, and consequences of substance use as well as treatment history and outcomes. You can contact your insurance company or check out Psychology Today to find a substance use disorder professional who can conduct as assessment.
The Partnership provides lots of guidance for Navigating the Treatment System, Understanding Treatment Options and much more within the topic of understanding and finding treatment for your child. Be sure to take advantage of these resources.