There is a part that has fallen down in front of the driver's side rear tire.

Was driving, heard a pop, looked in rear view but didn't see anything. Car was still driving but could tell it was handling different and could hear a noise occasionally. Drove it home (@ 20 miles from where I heard the original noise). Looked and saw the attached. It is only inches away from my rear tire (driver's side) and I can't get it to move up, down or sideways. Is this something I need to take to the dealer or could a local mechanic take care of it? What do you think would be an estimated repair cost?