Z.S.
Hi G.,
There's a really good site to find groups for support in your situation with a child with ADHD, it's called Meetup.com.
You should be able to find some support there or call the the Riverside County Office of Education, they may also have some places where you can get support and you may want to contact the city of Riverside itself. I hope you'll be able to find what you're looking for.