The most common cause of stomach infection which is usually amoebiasis and needs to be treated properly. The course of anti amoebic treatment with Metrogyl 400mg three times a day for five days should be taken. Ensure that good personal and food and water hygiene is maintained. It is usually recurrence due to reinfection. Further it should be ensured that there is no other associated disease. You should consult your family physician for better understanding of the disease and treatment.