I Have Active Ulcerative Colitis Left Side. I Am On

i have active ulcerative colitis left side. i am on prednisone which didn t work to reduce no. of b.m. nor diaerhia and now on imuran , while taering pred. i have about 10 bm between 8am and 11 pm and then a bm while im in bed at 1,2,3,4,6 am , why do i have bm s at those times when i eat in the day