My Son Is 34 Yrs Old. He Has Recently Developed

My son is 34 yrs old. He has recently developed abd pain of 2 days duration, somewhat constant, and somewhat sharp. No rebound tenderness, no fever, no nausea and vomiting. He feels achey, and very tired. His abd pain is in the lower stomach, no particular side. He has been having diarrhea stools. No history of Crohns, or any abd problems. Could this the the flu, or something more serious that I should follow up with our family MD. I have been giving him Chamomile and mint tea, gaviscon, and after resting, he said his abd does not hurt as much. Please advise.