Here's an article that describes a number of Crohn's-related skin problems, including EN. It describes the use of NSAIDs for the treatment of EN, but given the problems that NSAIDs are reported to cause the primary illness, that seems silly. It also mentions the successful use of Potassium Iodide. You would need a prescript
ion for this and would have to get tested for thyroid function during use, so talk to your doctor about
it. I found that my GI was really not interested in extra-intestinal manifestations of the illness. You might try your PCP or get a referral to a dermatologist. I mention potassium iodide because it is less dangerous than the steroids/biologicals which also should do the job. Here's the link: http://pmj.bmj.com/cgi/content/full/81/959/580
The relevant section is a bit more than a third of the way down the page - see the part headed "Management".