I get similar rashes when I am flaring. My doc tells me they are part of the disease and some people get them. They never caused much trouble, just worrisome because they aren't "normal." They always go away when my flare is gone. Not sure what is causing yours but if it does not cause any major problems I'd wait to see if it goes away. I'd make sure your doc knows just in case.
34 year old female, Diagnosed Ulcerative Colitis 5 years ago
Current Meds: Remicade every 6 weeks, Prevacid, Sustenex, Lialda, Lexapro (anxiety), Synthroid, Iron, vitamins, Fish Oil