Sending prayers for your son...
And for you.
Something for all of us to remember...what's available in one state, may not be available in another. I've been on this road so long, I can tell you with complete assurance and honestly, that RI has NO actually available program for those with dual diagnosed people. There's only two rehabs that take people on meds in the bunch, and just TRY getting into one without private insurance.
In RI, rehab is a lie.
Plain and simple.
And no, salvation army will not take them either. Fact.
I wish you and your son all the best.
Shalom!