I am a mother of a 4 year old have several niece's and nefews all ranging in age and disorders from bypoler to add w/athoritive disorders ext.. my advice is take away all the toy gun's for one and be adamit that fiteing and hurting is rong....he most generaly just needs something to hold his interest...so spend the weekend totally devotet to what he is doing and saying ask him things like do you like to draw.....draw with him....do you like to play pretend and dress up.do that with him as well...he may just be wanting a little exstra attention......this may or may not work but you both will have fun doing it ..enjoy each others company for the weekend and go from there.As for baby sitter you can contact his dr.or your local Dept of socal services and you can get a list of certified day car providers that are willing to watch overactive childeren..