How Should Stomach Pains, Vomiting With Initial Loose Motions Be Treated?

Hello Doctor, My mother is going through severe pains in her stomach for the past 3-4 days. Initially it started with heavy loose motions with green fluid being excreted, along with severe stomach pains during night. Later, for the next couple of days, the stomach kept paining during the day which aggravated during night times. The motions reduced after taking one lomotil pill. At this moment while I am writing this message, it is midnight time here, and she is again going through severe stomach pain with mild sensation for vomiting. We had consulted our family doctor today. She prescribed Rapeed D and Flagyl 200. She took the first dose about 3 hours ago. However, still there does not seem to be any relief from the pain. Could you help? Thank you in anticipation.-Neelesh