Hello welcome to the health care magic According to history provided white substance could be mucus or if very thin then could be worm... History needed regarding blood in stool?? Presence of fever?? Stress?? Etc... First investigation needed here is stool routine microscopic examination and USG abdomen... It could be Chronic colitis infection like condition or can be from malabsorption syndrome According to cause further specific treatment given If needed colonoscopy investigation can be planned for that Take care Hope your concern solved Consult physician or gastroenterologist for examination and discuss all these