Hello! Thank you for the query. Such symptoms can be caused by many diseases including bacterial intestine infection, parasites, food allergies, pancreas disease, peptic ulcers, partial bowels obstruction or even fistula between small and large intestine (due to inflammatory bowel disease for example). As it last 20 days, and no improvement, some diagnostics is necessary. She should start with full blood work, liver tests (AST,ALT,GGTP), amylase, lipase, urine amylase, bilirubin, urine analysis, stool tests, abdominal ultrasound. Upper GI endoscopy should be also done. If no findings in this tests, colonoscopy should be next and than abdominal CT with oral contrast (enteroclysis). Hope this will help. Regards.