I normally lurk, but wanted to reassure you. I have a 9 year old who has odd behaviors, as well, but his stem from a hefty combination of ADHD, severe learning disabilities and a language disorder. We were at our wits end until we took him to a clinical psychologist and were provided solid answers to what was going on with him. We still have bad days (boy, do we!) but now we have a toolbox to work from when the bad days come along. Getting those diagnoses was scary, but it would be a lot scarier having a 9 year old with his issues that we had no idea how to help cope.
As for dad: dads are almost always in denial about these things. I'm not sure why. But here's the thing: is it better for your kid to think he's a bad kid?
More than likely his behavior is caused by a cluster of neurological conditions. This means that it is medical in nature and knowing the cause means that you can begin to get a handle on helping your son deal with it. If he had diabetes, would you withhold treatment?