Fluids, rest, ED
The child's presentation is consistent with a viral gastroenteritis
, which is best treated by rest and lots of fluids (given in small sips).
However, you should schedule an appointment with his/her doctor to follow up should his/her symptoms persist. If at any point, the child appears listless or dehydrated, you should go to the er. You should also go if s/he can't hold down sips of liquid.