When I had an evil tropical tummy bug, the experienced doctor said I must not have milky drinks (OK by me - I dislike milk), dairy products and eggs. In other words, avoid proteins. I lived on white bread and honey for a few weeks and in the intervening 50 years have always relied on this diet when afflicted with 'winter vomiting' and the like. When we were little, Granny used to bring us her remedy, 'Bovril paste' - hard-boiled egg mashed up with Bovril - for everything including flu, measles, whooping cough and chickenpox! I liked it though I think my sisters had other ideas.