Welcome to HealingWell. I can certainly understand why you're confused by what the doctor told you. And if he told you people were "cured" by diet, I'd question his competency. I'd consider asking for a referral to a GI specialist.
You're correct in that ulcerative colitis starts in the rectum and presents an unbroken pattern for as far as it extends. However, there are other kinds of colitis - infectious, Crohns colitis to name just two. So I think first you need to clarify exactly what type you're diagnosed with.
Then I'd work on seeing a GI doctor to get started on appropriate treatment.
Good luck, and good on you for educating yourself!
Ulcerative colitis forum co-moderator
Moderate to severe left-sided UC diagnosed 2001. Flared for 5 years, finally in remission with Remicade since March 2006. Colazal, Remicade, Nature's Way Primadophilus Reuteri.
Avascular necrosis in both shoulders is my "forever" gift from steroids.
Chronic joint/connective tissue/muscle pain; TKR 05/09
"My life is an ongoing medical adventure"