DS (19MO) seems to have some sort of vomiting bug. He was fine this morning but threw up spectacularly after lunch. I put him down for his nap but he woke up after 30 mins or so and threw up all over his cot. He's now completely emptied his stomach but is having intermittent episodes of retching up bright yellow bile. Does he need a doctor? Should I try to give him food, or just water? Any advice welcome. Thanks!