Hello, this is Kitt. Welcome to Healing Well.
There is a skin rash that is associated with Crohn's.
Erythema nodosum may be associated with inflammatory bowel disorders (Crohn's disease and ulcerative colitis)
Erythema nodosum results in reddish, painful, tender lumps most commonly located in the front of the legs below the knees. The tender lumps, or nodules, of erythema nodosum range in size from 1 to 5 centimeters. The nodular swelling is caused by a special pattern of inflammation in the fatty layer of skin.
I would suggest you see your GI physician to see if indeed you may have Crohn's if that is what you are concerned about. Many other things may cause a rash or allergic reaction.
Take care and keep posting.