Becky I'd think it's VERY likely related. My DS is dairy intolerant (in fact we are about to start trying again tomorrow - starting with real organic butter) but one of his first signs was major behavioral changes. He'd turn into the Tasmanian Devil - which is SO not like him. If too much dairy he'd also get physical symptoms - blow-out diapers, tummy cramps and nasal congestion. But as of a year ago even trace amounts of dairy would REALLY affect his mood/behavior.