Yeah - I would have said 6-mp or Imuran too.
The trouble with those is that they typically take 3 months to start working.
It is possible that a similar drug to asacol would help you. Sulfasalazine was my first drug, and then I was moved to asacol. When asacol quit, I took pentasa with good results for a few years. There are several different 5-asa (I think they are called that) drugs.
Maybe you could try entocort instead of prednisone? It's similar, but a bit weaker I guess? My doc wouldn't let me take it instead of pred becasue it wasn't as strong, but many members here have had good luck with it.