The other thing to look into, if food elimination gets you nowhere, vitamin/mineral deficiencies and excess heavy metals (eg. copper) can be a cause for behaviour problems as well. I think it's a hair test for the metals and a blood test for deficiencies. When I attended a talk by Dr Alison Knight, who works in the field, she said that even if vitamin/mineral levels are at the low end of the scale supplements are recommended. This is aparently because the 'healthy range' that comes with lab results changes over time, so as the general population start to have lower levels of, eg. iron, the range lowers to reflect this.