My daughter had same problem. She had three polyps removed from her colon and this stopped it. two were cancerous.
I have been diagonised with Dumping Syndrome also. What other symptoms do you have besides diarrhea? Normally, food is digested and mixed well by the stomach. In dumping syndrome, food moves into the small intestine too quickly, causing nausea,diarrhea, cramping, palpitations (skiped heart beats and rapid pulse), sweating and sometimes faintness. I was advised to eat smaller- low-carb meals, avoid sugar and do not drink with your meals. I also, have to avoid corn products and pastas. I hope this helps.