Hi, Welcome to health care magic, Chronic diarrhea can be caused by bacterial infection,Lactose intolerance,bowels obstruction or inflammatory bowels disease but it has no much relation to your RNY gastric bypaas which was done 10 years ago. I kindly would like to ask you some questions like: 1)do you have blood in stools? or 2)do you have fever? 3)do you have some times diarrhea and others constipation? 4) if you have done investigations like blood work, biochemical tests,stool tests and colonoscopy then please share those to me or you can go to your family physician for further consideration. If I were your treating doctor I would recommend you to run further test if they had not been done previously. 1) repeat examination of stool for ova/parasites 2) culture of stool You will require antibiotics (quinolones or cephalosporins or antiprotozoals etc.) with antiemetic, antispasmodics and antiinflammatories with prebiotics and probiotics. There will be a need of fluid and electrolyte balance in body.So,take plenty of water with electrolytes and fruit juices. You must consult physician for further treatment Regards.