Saturn, I am so sorry to hear about the challenges your lovely young guy is going through. You are absolutely right to take the possibility of mood disorders seriously; eight, unfortunately, is not at all too young.

However, lots of providers out there still think of mental health as an adult problem, despite an abundance of research that most major issues start in youth or adolescence. So your challenge is to find a provider who takes you seriously, AND knows what they are doing with an 8 YO mixing in gifted and ASD. Unfortunately, I only know the Canadian end of the scene. My general suggestion is to start asking for names through research centres, where they'd be more familiar with more complex situations. I started with the NIH National Institute for Mental Health, and came up with a couple of #s:

Substance Abuse and Mental Health Services Administration (SAMHSA) Treatment Referral Helpline at 1-800-662-HELP (4357). SAMHSA also has a Behavioral Health Treatment Locator at https://findtreatment.samhsa.gov

https://www.nimh.nih.gov/health/topics/child-and-adolescent-mental-health/index.shtml

National Institute of Mental Health Information Resource Centre, 866-615-6464
Also has an online chat; scroll to very bottom of the NIMH link above

Also, I recommend talking to the National Alliance on Mental Illness, 1-800-950-NAMI (6264) or info@nami.org
https://www.nami.org/Find-Support/NAMI-HelpLine

Trust yourself, and keep calling until you find somebody who *listens*. Sending huge hugs.