Dehydration And Abdominal Pain Immediately After Taking Food. Is It Possible To Still Have Loose Stools And Intestinal Intercession?

My son was seen in the ER Friday night secondary to belly pain, mind you this child gets a GI bug if you look at him the wrong way, he is 5 but this time was different because his pain was localized and worse so I wanted to rule out appendicitis, which we did through palpation and listening. Syptoms stayed the same through the weekend and we saw the pedi on Monday and were sent to the children's hospital ER. He was treated for dehydration and a second diagnosis of GI bug was given, they did however do a US and saw an intestinal intercession but it slipped in then back out, the radiology doc stated that it was nothing to worry about, it was just because of the inflammation in the GI tract. No tonight he is still ill but has better moments but if he eats even the smallest thing he has belly pain again, which causes crying. My question is this, do I need to watch for anything with him and is it possible for him to still have loose stools with and intestinal intercession?? When do I take him back to the ER if I need to?