You seem to have developed viral gastroenteritis
.There is no need to take any antibiotic at the moment.
Since there is no blood in stool
,no fever ,you don't need any antibiotic at the moment.
You only require oral rehydration solution so as not to develop any dehydration
You would require to go to ER only if you are having vomiting
and not able to take orally.
In that case you would require intravenous saline.
So at the moment just take plenty of oral fluids and go to ER if you develop some complication like blood in stool.