I am trying to figure out what my son is struggling with. He has had a stomach ache off and on since last saturday. At first we thought it was pre-camp jitters, but he called me from camp tuesday saying he wasn't feeling good, and at that point we thought maybe he was homesick. I went and got him. Wednesday night he still wasn't feeling good and was having pain on his right side. I took him to the ER concerned that it might be appendicitis. They did an ultrasound as well as an MRI and ruled appendicitis out. He still is not feeling well. He has not had a fever this entire time, and has not thrown up, though there were a few times he was close. He is 11 years old, and I'm currently questioning if it could be Irritable Bowel Syndrome. Any thoughts?