I warned my 9 year old that she would be promptly shipped off to rehab if she was discovered to be using ANY kind of drugs. I repeated this often throughout the years.. she's now turning 15 and the offer still stands.
I think that is what I would do. Rehab or INpatient counselling. This IS as serious as it gets IMO.. what would I want to wait for.. something worse? Something irreversible? Not me, not her, no way. So.. for me... counselling and continuing with life wouldn't be enough. The time for talk was before... when dealing with an emergency, we must first triage, then move onto stabilize and rehabilitate. I follow the same procedures with her emotional status best I can.
I was rebellious & self destructive, and I've never ever met someone who was that was that way for NO reason. There IS a reason, no matter how small someone else might think it to be, and the reasons can destroy us when we don't know how to cope with them.
Good luck, and I hope the solution that fits your family best comes to you.