Ryan's trip to the ER - an unsolved mystery

So yesterday we were going about our day as normal Ryan had taken a nice long nap and then we went to Shelly's for our craft play date. Ryan was playing and having fun with the other kids and then he started screaming. He pointed to his diaper and said "ewww" when Katie checked him there was nothing there. Ryan continued to cry and scream and grunt and nothing could calm him down, not mom, not dad, not a popsicle, not ice, nothing was calming him down. Ryan continued to scream the most intense "i'm in severe pain" cry we've ever heard. We decided to take him to extended care to see if we could get him some help. His stomach was obviously causing him severe pain and there was nothing we could do for him. Ryan can not throw up because of the surgery he had as an infant and nothing was passing through the other end so there was nothing we could do to help relieve the pain and pressure. When we got to extended care he had been screaming so much he was blue in the face, they thought he was having an asthma attack or some other respiratory trouble and called an ambulance. They put Ryan on an oxygen mask and tried 4 different times to start an IV and were unsuccessful. At that time the ambulance arrived and decided he was fine without the IV and took him off the oxygen. Ryan and Katie got to take their first ride in the ambulance and Mario followed behind. Ryan screamed and screamed still and finally fell asleep during the ambulance ride. At the ER Ryan slept and slept he woke up while they performed a few tests and then slept some more. Ryan developed a fever while in the ER so they gave him a dose of Motrin and after that he was up and ready to play. The test results came back he did not have a UTI everything in his lungs and stomach looked fine, there were no obstructions and no obvious reason why he could have been in so much pain. Since he had not had any recurrence of the pain while in the ER they sent us on our way and told us to bring him back if it happened again because that could be an indication of the intestines slipping inside each other but from the initial tests and observations the doctors did not think that was the problem. Could have been an air bubble? bad cramps? piercing abdominal pain caused by who knows what? Whatever it was it went away and we will just be keeping a close eye on him and hoping it doesn't happen again.