Silkstalkings, pretty much same environmental factors here; breastfed til 11 mths, fish oils, calm household, very well behaved sister, no upheavals of any kind (no death, no divorce, no health problems, never even moved house), close knit extended family, good diet, limited screen time, regular bedtimes, but still he goes nuts over nothing.
Every little element of life can provoke a meltdown, we still have to dress him, wash his face and clean his teeth, every bath/shower provokes a meltdown, he won't wash his hands, won't put on his own shoes, constantly hurts his sister for no logical reason, the list goes on...
This morning the walk to school was accompanied by screaming, shouting, crying, punching and kicking. I am almost immune to the stares and comments of others but it is still hard to bear. Apparently it was because his shoes were getting wet in the rain but really its the nervous anticipation of another day of school related demands. When we got to school he said ' I don't want to stay here on my own without you, I'm going to get shouted at. I'm not like all these other children, they don't like me' 
For me, pathological is exactly the right word: "characterised by an unhealthy compulsion". It is a compulsion and it is unhealthy, for me and for ds. Silkstalkings "the concept of demand is a particular neural pathway formula (or something more scientifically accurate, ykim) and theirs has a little alarm on it or maybe it's shorter and gets processed quicker than everything else" I think this is a great way of describing it. The problem with childhood is that your entire life is taken up with doing as adults tell you and that neural pathway alarm is constantly ringing!