My car has been making what I can only describe as a thumping noise when I let off the brake or make a turn. My check engine light is off. It almost sounds like it is coming from somewhere near the front left of the vehicle. I checked for loose lug nuts and to see if anything was stuck under my car, and there wasn't anything. I am also a university student and have no other means of transportation to campus for the next few days. Do you have any ideas on what it might be and how urgently I should get it checked out?