If you swing between D and C, then maybe yogurt might help.
If you are tired, maybe you are iron deficient, but check out the lab results to be sure - not just hemoglobin, but also ferritin (single most important test for iron, tests iron storage), serum iron, transferrin sat, TIBC. Few docs I've met even know how to test for iron. I literally spelled out ferritin for the person who drew blood, and he still failed to test for ferritin. My daughter's iron levels plunged in just two weeks on Pentasa, a mesalamine, even though she was taking 25 mg daily iron supplement. So now we're going to try doubling the iron supplement, to see whether the suspected effect of mesalamine on iron absorption can be overcome.
You can get copies of your lab tests and learn to read them with the help of www.labtestsonline.org. The web site also lets you know how to test for various vit and mineral deficiencies.
We found the current gastro to be clueless about iron and vit D (my daughter was deficient in both) so we went to an endocrinologist. However, because medicine is so specialized the endo, unlike a GI, wasn't a Crohn's expert so he didn't know how to modify vit D and iron treatements for such patients. I found medical journal articles that talked about the effects of vit D and iron supplementation on Crohn's patients. He used the articles to help treat my daughter. So at least he was willing to work with the patient. The gastro was too arrogant to read either article, so he keeps confusing her iron deficiency with the kind caused by Crohn's, not the regular kind many women have.