When I had mysterious "shoulder" pain (doc sez: referred pain from the diaphragm, but I don't think your organs are dying /shrug) the doctor said I could take up to 11 Aleve a day for up to 2 weeks before I started really killing my liver, and up to 6 a day on a semi-long-term basis. Plus you can combine NSAIDs with Tylenol for extra pain control.

Other than that, heat on the stomach, don't drink cold things?