Hi ! Good evening. I am Dr Shareef answering your query. Even though the history of improvement in the intensity of pain points to the non seriousness of the abdominal trauma, to be certain, I would advise an ultrasound abdomen for your son after examining him clinically. If negative, I would simply advise some anti inflammatory drug along with a proton pump inhibitor drug. I hope this information would help you in discussing with your family physician/treating doctor in further management of your problem. Please do not hesitate to ask in case of any further doubts. Thanks for choosing health care magic to clear doubts on your health problems. I wish you an early recovery. Dr Shareef.