Welcome to the Medical Clinic at the Interplanetary Relay Station is what short fiction can do pretty well--humor. You don't want a joke to take forever. There is no hope for actual help, but the path to non-help is pretty funny. It's written like a choose-your-own-adventure book, but not really. Which was fun, because I used to like to try to read those things straight through and try to keep the plots straight. A good 3 stars.
This one was indeed a contender, but my favorite for the Nebula is Seasons of Glass and Iron, by Amal El-Mohtar. Go check that one out.