My daughter takes Solgar's "Gentle Iron" with OJ...two hours after taking any meds or vitamins or food (which all interfere with iron absorption) and one hour before taking any meds or vits or food. No problems at all.
An iron infusion might be the way to go. Anemia not only makes you tired, but lowers your resistance to viral and bacterial infection. Also lowers cognitive and learning skills. If you'd like, I can email you a medical journal article that talks about how iron is best treated in Crohn's patients. It spells out exactly which kind of iron is best infused, the infusion rate, the quantity, etc.