I know this is kinda gross but I have had diarrhea for 5 days straight and it isn't getting better... why?

Okay, so I have Ulcerative Colitis (i you don't know what that is then click here a href="http://www.nlm.nih.gov/medlineplus/ulcerativecolitis.html" rel="nofollow"http://www.nlm.nih.gov/medlineplus/ulcer…/a ) and I have to take medicine for it. I did a little research on my medicine and it said that the severe side effect is bloody diarrhea, but i have been taking that medicine for a year now and haven't had any of those side effects until now. What do you think it is? I am going to the doctor today and I got to stay home from school because of it. Can somebody PLEASE help? I want this diarrhea to go away! OH! And Ulcerative Colitis has no cure unfortunately =(