Young Child w/ Mood Disorder- Seeking Psychiatrist, Therapist etc

I'm looking for recommendations for medical providers for my 6-year old child who has a manic-depressive mood disorder (disruptive mood dysregulation disorder).  These types of disorders are not universally considered or understood by all pediatric practitioners, so we're hoping to find treaters who are both understanding and knowledgeable about them.  We're interested in recommendations for pediatric psychiatrists, developmental and behavioral pediatricians, therapists/psychotherapists, and group therapy.  If anyone knows of DBT practitioners or groups for children this young, that would be fantastic, but we're open to other modalities too for sure.  I know many places may have waitlists, and I'm willing to get on the lists to get the ball rolling.

Any additional resources, books, websites, parent support groups, etc are also welcome.  Thank you very much!  Your kind support and resource suggestions are greatly appreciated.