my 4 year old son had an appendectomy 4 days ago. He is eating well, drinking well, has had his first bowel movement a couple of hours ago. He is in great pain in the mid to upper right side of his belly, and his belly seems enlarged - thought it would have gone down after the bowel movement. If it is wind / gas pain, is there anything I can give him to help?
From your history pain in upper right side and mid-region can be suggestive of Acid peptic disease. Bt as he takes food normally this is unlikely. I would give Rant ac syrup and observe. If it is coming frequently OGD (esophagi Castro duodenoscopy) with thin flexible tube is painless and confirmatory. An ultrasound test can also be considered. For relieving gas as you asked, I would give a carminative syrup marketed as Carmicide-P and see. The description that the distension went away after bowel movement points to gaseous distension.  Well did you say appendectomy done 4 days ago? Is he in hospital? Check with your doctor this was not mild gastric paresis due to surgery, although it is harmless common finding postoperatively. You can review with your doctor. Regards