Hi,
Welcome to health care magic,
The symptoms of stomach pain with nausea,diarrhoea could be due to
irritable bowel syndrome,dyspepsia,sprue,bowel obstruction etc.
If you have
abdominal pain or distension with vomiting,diarrhoea and constant pain then you should start some medication like
proton pump inhibitors (
pantoprazole),antispasmodics,pain killers with avoiding excess carbohydrates and fatty foods, avoiding oily and spicy foods.
You should do some routine blood works,ESR,electrolytes and if required then
ultrasound abdomen.
With symptomatic treatment you will feel better within 2 to 3 days and If you still have these problems then you should go to gastroenterologist to treat underlying cause.
You might also need to undergo upper GI endoscopy if symptoms remains persistent.
Regards,