Last meal was Friday, followed by a tummy upset where he needed changing every hour and was very distressed. Saturday he sat on the sofa watching tv all day and wouldn’t speak or play. His behaviour was back to normal by Sunday but he won’t eat. He cries if I try to put him in his high chair or even just say the word chair. He runs away crying if I offer food. He’ll only have milk, and a few chips off my plate yesterday but nothing today. At what point should I get worried about his refusal to eat?