I have the same problem. I was severely anemic a few months ago and while I have recovered and my bloodwork looks almost normal, I am still not 100%. When you get your iron levels back up, you will feel better. I am still not in 100% remission - that probably contributes to my fatigue, probably the same for you. At least we aren't losing blood anymore, that will help heal you and improve your blood. I take enzymatic therapy "ultimate iron" supplements. They seem to help me and don't cause bad side effects. I used to take the iron 3x a day but now I am down to 50mg. I also have back pain and aneck and shoulder pain.
Diagnosed with mild proctitis in March 2007: Treated with Canasa (as needed)
December 08: Began treating with Asacol 400mg (9/day) + Canasa 2x/day - Anemic
May 09: Off Canasa, taking Asacol (9/day)
Back on Canasa every other night + Asacol (9/day) + Probiotics + Iron
Reducing to 6 Asacol/day + Canasa + Probiotics + Iron - So far so good!!! -SPOKE TOO SOON! Back to 9/day...