Donald Jensen.
http://medicine.uchicago.edu/faculty_profile/faculty_profile.asp?empl_id=9013
Try Dr. Kim at Northwest Gastro on Arlington Hts. Rd. in Arlington Hts. Might be a little far for you if you're in the downtown area, but he's good, patient, knowledgeable, listens, doesn't rush through appts. (though sometimes that means a longer wait in the exam room while he's with someone else). Plus the staff is friendly!
Dr Blei and Dr Flamm at Northwestern, Div of Hepatology