My guess is you were not put on a high enough dose of steroids for the severity of your flare and/or were started on a taper too quickly.
In spite of what doctors will say, my experience is that the foods you eat and the consistency makes a huge difference when you're in a bad flare. You want foods that will easy for your impaired system to digest. Broths and soups are great. Veggies and fruits need to be peeled and cooked to softness. Soups and veggies can even be pureed. Safest meats are tender white meat of chicken or turkey that's baked, roasted or broiled.
Even doctors often prescribe a low residue diet for folks in severe flares or just out of the hospital.http://en.wikipedia.org/wiki/Low_residue_diet
Diagnosed with ulcerative colitis spring 1999. Have been in remission for years with only a few minor blips. Scope on 6/22 showed no inflammation at all.