"i have symptoms of diarrhoea, vomits, yellow urine and fatigue and severe stomach ache..what can?

You could just have the stomach flu (Viral gastroenteritis) or food poisoning. The yellow urine is most likely caused from losing fluids, so try to drink lots of clear liquids. You don't want to dehydrate. Sip the drinks slowly, you may feel the need to vomit or use the restroom, but the main thing is staying hydrated. If you don't start feeling better soon then its time to see your doc. Hope you feel better soon!