You've got some great advice so far, and we all know the feeling. *hugs* and hang in there hon!
In addition to proper testing, proper medication (because every kid and situation is different), I'd also like to toss in getting them allergy tested on top of this. Some food allergies can also show up as behavioral problems and some of us have found that special diets for our kids help (not eliminate, but *help*) the problem. For some it's a gluten-free diet, for some it's dairy-free, for some it's a dye-free diet, for my own daughter it's a diet with lots of whole grains and omega-3s but without processed meats. Allergy testing may show up something or it may not. Food diaries can be helpful to keep because you might start seeing links in what (or even when) meals are eaten to behavior. Some kids lack certain nutrients in their diet (like magnesium) and that can cause behavioral problems, too.
No ONE way will fix everything or is right for every kid - you've got to find the paths through that are right for your kids, and there will be trial and error involved with that. We'll be here for you every step of the way, too. And you've got to find time for yourself, too.
