Hello Jonathan and welcome.
You've found a great forum here, full of advice, support and help.
First off, some questions.
1) Who diagnosed your son with ADHD/ODD?
2) What was his early development like? Any speech delay, any issues with fine motor skills
3) Does he have any issues with eye contact?
4) Does he have any sensory issues, such as sensitivity to touch, noise, light etc.?
5) Any unusual play habits, e.g. lining up or spinning toys?
6) How does he do with transitions from one activity to the next? Are they difficult?
Sorry to fire so many questions at you right off the bat, but they really help us to point you in the right direction.
ADHD/ODD is often a starting point for a diagnosis, rather than a conclusion. So many childhood issues present with hyperactive behaviour and ADHD is the most obvious diagnosis, so usually the one we're given first. As for ODD, it describes behaviour and it's often a symptom of a deeper issue, rather than a stand-alone diagnosos.
Just an example: My difficult child, who has Asperger's syndrome, bipolar and a few other things, was initially diagnosed ADHD/ODD. The mania from bipolar looked just like ADHD behaviour, and the oppositional behaviour came from our mishandling of him because we didn't know about the Asperger's or the other issues. Once we had better information about what was truly wrong with him, we were better able to help him.
Others will be along to weigh in with advice, support and help.
So glad you found us, but sorry that you had to.
Trinity