Like others, am sure it's mostly the Crohn's BUT you might want to have your iron, B12, and folic acid levels checked. The serum iron test is useless - your hemoglobin (hgb) is a better indicator, along with a Ferritin test (Ferritin is the stored form of iron in your body). Both the meds and disease can cause nutritional deficiencies.
You might want to consider more effective meds and trying a dietary regimen like SCD or Maker's Diet. It's not good to let the disease fester because it is only partially controlled by meds. Pentasa doesn't do much for most Crohn's patients. Entocort works in some, but not all, but has NOT been proven to provide full remission (in other words, no symptoms, good labs AND a clean colonoscopy).