I am sorry that your question was unanswered for long.
A persistent diarrhea with occasional blood would require a colonoscopy and CT scan; as soon as possible. The causes can be;
1) Inflammatory bowel disease like Crohn's disease or ulcerative colitis.
4) Chronic infection
5) Parasitic infestations.
The initial evaluation of diarrhea is on these characteristic;
a) stool volume,
c) consistency, and
d) gross appearance.
This description to use the term "diarrhea" to describe urgency and the frequent passage of small-volume stools suggests a functional disorder such as IBS.
Stool volume can give an idea of disease location and underlying mechanism.
a) Large-volume stools (more than one liter per day) would point to small bowel disease and secretory diarrhea.
b) Small-volume stools (less than 300 ml per day) suggest large intestine diseases and functional gastrointestinal disorders like IBS.
Stool consistency can be varied ranging from formed to watery, and correlates with the rate of intestinal transit.
a) Secretory diarrheas are liquid.
b) Functional diarrheas are soft or semi-solid.
c) Stool floating will be indicative of if being filled with gas from fermentation of mal absorbed carbohydrates.
d) Mucus can point to both inflammatory and noninflammatory diarrheas, such as ulcerative colitis and IBS.
Stool appearance helps to classify diarrhea as;
a) Watery diarrhea is caused by carbohydrate malabsorption, medications, bile acid malabsorption, Crohn's disease, microscopic colitis, chronic mesenteric ischemia, post surgical diarrhea, hyperthyroidism, colonic adenomas and carcinomas, alcohol induced diarrhea, laxative abuse, and hormone-secreting tumors.
b) Steatorrhea or fatty diarrhea is greasy, oily, foul smelling, bulky, or voluminous stools that are often difficult to flush, might contain undigested food particles, and sometimes leaves an oily stain in the toilet bowl. These characteristics suggest pancreatic disease, short bowel syndrome, celiac disease, giardiasis, and small bowel bacterial overgrowth (SBBO).
c) Bloody diarrhea suggests Ulcerative colitis, Crohn's colitis, cancer and chronic infections.
Please feel free for your follow up questions.
I would be happy to assist you further, if you need any more information.