If you are not a known patient of inflammatory bowel disease
disease,then you are most likely suffering from food poising which may be caused by bacteria,virus or parasites.
Take some OTC antispasmodic medicine for your pain abdomen ,take plenty of oral fluids and rest.
You should be alright in next couple of days.
If your condition worsens or you develop severe vomiting
or develop high fever
,then you should not wait and go to ER immediately as that is the indication for intravenous fluids and possible antibiotics.