Hello and welcome, Short incubation period and abrupt onset of the symptoms are highly suggestive of food-borne infection (food poisoning). Bacillus cereus infection is highly likely. The infection causes 2 types of illness: diarrhea type and vomiting (emetic) type. The vomiting type usually starts within 30 min to 6 hours after ingestion of food and causes nausea, vomiting and abdominal cramps. Re-heated leftover rice is a frequent source of infection in which residual bacteria release toxins which cause the disease. The other foodborne infection which may cause similar signs and symptoms is staphylococcus aureus. Both of the infections are usually self limited and requires only supportive care. Try to drink enough fluid rich in electrolytes to avoid dehydration. You can simply make oral rehydration solution by adding 6 tablespoon of sugar and 1/2 tablespoon of salt to 1 liter of boiled water and add 1/2 cup of orange juice. Take enough rest. The disease usually resolve within 24 hours. If you have high fever, severe/bloody diarrhea or severe vomiting please contact your doctor. To confirm exact cause of the disease requires laboratory testing and your doctor may also prescribe antibiotics. I hope the above information will be helpful for you. Please, feel free to ask me if there is anything else you need to know. Thank you, Malik Amonov MD