DS1 aged 5 is instantly sick when his little brother poos aged 5 months, I try and keep him away when he poos, but obviously U can't keep on 24 hour watch, he vomited everywhere just before school. He is so sensitive to smell about the poo, so much so he won't come upstairs if I am changing and has a moaning fit and starts to gag. What is all that about? Any ideas? It is bizzare and becoming a problem!