My 8 yr old son sees Allan Gonsher in Overland Park. He has made a huge difference. Phone number is ###-###-####, although I'm sure that will be changing, as he is moving offices to 95th & Metcalf. He is actually from Omaha, but spends half the week here in KC.
Children's Mercy has an unbearable wait time to see someone.
Marillac is a pediatric psychiatric hospital that you can call if you are in crisis. My niece was just there a couple weeks ago, and it seems like a wonderful place. They are just east of 127th & Antioch.
If you are looking for someone to help you determine if there is an underlying psychiatric disorder, you will need to see a psychiatrist, not a psychologist. Psychologists/therapists do not write prescriptions. The psychiatrist we see is actually a nurse practitioner, but we really like her. Her name is Nancy Pierce and she is also at the above number. She sees both my 8yr old and my 11 yr old son, as well as myself.
Another option is to call the Johnson County Health Dept. They also offer services and referrals, although we have not taken as much advantage of this as we should.
It does sound like there could be something underlying with the sudden shifts. Also, don't forget he's hitting puberty and some moodswings are to be expected.