My ex specialises in getting kids diagnosed with ADH naughty behaviour diagnosed so the parents can really cash in.
look for a book called 'don't shoot the dog'
amazing lady who trained all kinds of animals including, and I quote 'truculant teenagers'
basically she gives you the tools to change your life.
I'm pretty much victorian dad so I've never had problems with my kids and my familes kids.
Still quite confused why kids in the 21st century are not naughty any more,and are all just AD.
As he's only 4 ,its best you wait it out a while.
This website is from a support group and has lots of good advice and a helpline number you can call: