You're right. Trust your gut. You know your kid best. My experience with Explosive Child was that it helped us reframe our thinking. The "If they can do good, they do" really resonated with us and changed our approach. And yes, five is young for the level of digging down and communicating, but it helped us understand the meltdowns over seeming silly things.
As for finding therapists, the kids had Kaiser insurance at the time, and he went through the gamut of groups and ever-changing therapists. They weren't there to talk and listen, mostly to prescribe drugs. And then I sat on phone for hours trying to find private therapists that could do drug therapy if needed, that his insurance would be accepted, and that specialized in kids like this AND had room on their caseload.
My grandson has done so well because he has wrap-around services now. The scattershot approach from schools and various things tried on IEPs and instructional aides etc., just didn't work. When the violence really escalated to the point that elder abuse services was called on my grandson (when he was 12) because of serious injury to my husband, and child protective services was called on my husband (who was trying to get my grandson out of the car and in trying to drag him out, left a small mark on his neck). CPS came into our home, as did the elder abuse people and they said that we might have to get police and residential type services involved. We were not charged with anything and they said that we definitely needed additional services.
About that time, he lost it at school and the police had to be called to the school. He tore the school up pretty good and hurt one of the secretaries. He was moved immediately to a behavioral school and that has saved us. He's had the same talk therapist for 18 months, one hour every week. Occupational therapy to find sensory strategies help regulate, etc. Lots of interventions and it has worked. He has had trauma, ADHD, generalized anxiety disorder, no autism, but a word salad of other DSM diagnoses over the years. Which described what was being seen at the time but didn't seem to get to the heart of things, and it's changed over time.
I don't know where you are located and services are so different in different places. We've tried private therapy where the psychiatrist played video games with him. And he prescribed drugs that didn't work very well, either.
Grandson is now 14, no drugs (we tried so many, then did genetic testing for his ability to metabolize various classes of drugs, which helped guide us for awhile). I have nothing against drugs that work, but for him, they just didn't. And lots hard work on his part. And our part. Sigh. It shouldn't be this hard, right?
Wow, that sounds so challenging! Having police called to the school is one of my great fears ... and obviously whatever behavior led to the police being called is a major fear, too ... I hate hearing that he's hurt someone.
I take medications myself, but in my son's case I don't know what they would be medicating for, you know?