I also have Crohn's in the terminal ileum, with intermittent abdominal pain and occasional fevers--no diarreah. I was told that it is not unusual to have no change in bowel habits if the inflammation is only in the terminal ileum; however, if the area is narrow you are at risk for an obstruction or perforation, which means hospitalization and possibly emergency surgery. The barium test will help you determine whether the ileum is significantly narrowed.
I spent about six months trying dietary control but was unable to get back to feeling 100% normal unless I stayed on an exclusive liquid diet. Then the doc tried (successfully) to convince me that Entocort may be my ticket to feeling well and "possibly" avoiding obstruction/surgery a little while longer. So I just started Entocort myself a few days ago. Entocort has fewer risks/side-effects compared to other IBD treatments. So far the only issue I have noticed is some dizziness, crossing my fingers that's the worst of it.
Your arthritic symptoms and rash may also be helped by getting the Crohn's under control. If obstruction is not an issue, maybe you could consider trying a dietary approach first ( if you are willing to limit your diet). There are several options--going on exclusive enteral nutrition, trying something like the Maker's Diet or Specific Carbohydrate diet, or even just eliminating gluten, which helps some people.