Hi there Ryan,
Sorry to hear about your emergency.
Very few of the standard rental car companies (Hertz, Budget, Avis, etc) will rent to people under age 21 (and even then there are huge fees)... unless you are in the military.
However, Rent-A-Wreck does rent cars to people 18 and older.
Are you trying to rent the car in Chicago? If so, you'll need to take a cab to their location:
Let me know if you have any questions. If not, thanks for pressing "Accept".
Really? They claim to on their website. I'll opt out to see if any other expert can find you one that does.
Another expert has kindly pointed out this discussion:
You might be able to rent a moving truck!