Hi Mike,
My GI doctor will not perform a colonoscopy while I am flaring, so I would look for another gastro doctor. However, when I was hospitalized they did do one. They just wanted to see how far up the UC traveled. Mine is confined to the rectal area so I assume it is just ulcerative proctitis.
Your Colazal dosage seems a bit high, but it may go according to body weight. My doctor has me take 9 pills a day when flaring. Did you try Cort enemas? They work pretty well. When flaring I had a bit of a problem retaining them so the doctor prescribed Canasa suppositories. Is your GI doctor aware that your condition is worsening? My last flare, which started in April of this year, lasted for seven months. I, like you, had a hard time getting off the prednisone. Whenever I was weaned off I was only able to enjoy two weeks of remission before relapsing. The last relapse the doctor increased my initial dosage of prednisone to 40 mgm of prednisone instead of 30 which he usually started me. My taper was 10 mgm a week until the final week which was a 5 mgm taper. I believe the 6MP finally kicked in too which led to this remission. Ask your doctor about the 6MP.
Good luck to you. Oh and one more thing...I don't know what your diet is like, but while flaring it is best to follow a low residue diet.