Bread / dry toast fingers
Plain rice or pasta
Sugary, spicy or rich foods. Keep everything stomach-calmingly bland.
Fruit juice/squash/flat lemonade - too much sugar can stimulate diarrhoea.
Sports/electrolyte drinks - these are for adults only and are not suitable for kids.
Nothing but water. Keep offering food or his usual milk and, if he really won't eat anything, try a lolly or a rehydration drink, available from pharmacists.
If the diarrhoea and vomiting lasts for more than 48 hours, seek medical advice. Babies under 6m may need medical attention sooner, so seek medical advice. If he's older than 6m, seek medical advice if it lasts over 24 months.