Ulcerative colitis  is an inflammatory bowel disease (IBD) that causes long-lasting inflammation and ulcers (sores) in your digestive tract. Ulcerative colitis affects the innermost lining of your large intestine (colon) and rectum. Symptoms usually develop over time, rather than suddenly.
It is often caused by bacterial infection  ( Entamoeba histolytica )which destroys the intestinal wall leading to ulcerative colitis or amoebic colitis. Patient often has lower abdominal pain with passage of blood mucous and urging of stools soon after eating , because pressure of food  or gas formed in the congested colon cause frequent urging of stools
Second common cause is Giardiasis caused by micro organism called Giardia. This condition is common in children throughout the world , especially in Asian countries . Common symptoms are nausea, loss of appetite , abdominal pain, slimy stools mixed with indigested food
ARGENTUM NITRICUM 6—Great distension of the stomach with much flatulence. The stool is green like chopped spinach. Diarrhea immediately after eating or drinking. Loose motions made much worse by anxiety or fearAnticipation of an ordeal, such as an exam or interview, may produce the symptoms
AMONIUM CRUDUM  30- Diarrhea alternates with constipation.Tstool is slimy with much mucus, but also contains hard lumps. Tongue coated thick white. Cravings for acids and pickles
MERC COR 30- Great urge to pass stool, even immediately after defaecation. The stool is hot, bloody , slimy and offensive. The abdomen feels bruised and is bloated and very painful to the slightest pressure
MERC SOL  30-Stabbing abdominal pain and the stool is greenish, bloody and slimy. All the symptoms are worse at night
SULPHUR 200—Head remedy for colitis. Start treatment with this remedy
CHINA  30—Colitis is brought on after eating fruits or ice water. Yellow watery stools with flatulence, painless and worse after eating
TUJA OCC- 1M- Anexcellent remedy for colitis