This was supposed to be included in Montage of Heck but was cut. In it, Kurt appears to be really, really ill with his mysterious stomach ailment and is feeling awful after a day being subject to medical tests designed to figure out what, exactly, was wrong with him. The clip is instructive in the sense that it gives us an idea of how Kurt was suffering with these legendary stomach issues.
Vomit is involved. Watch at your own risk.