What causes vomiting and diarrhoea in cats?

The following are examples of what may result in vomting and diarrhoea in a cat.  

• Dietary indiscretion.
• Viral infections.
• Salmonella from catching and eating birds.
• Intestinal obstruction from eating something that has gotten stuck in the intestinal tract.
• Pancreatitis
• Chronic inflammatory diseases
• Kidney and liver disease.