A Problem with my Grand Prix

Hey I own a 1992 Grand Prix LE and all of a sudden from the rear drivers side there is a clunking sound. At first I thought i didnt full close my trunk but I did, and then I thought maybe my tires were low on air..none were off by more then 2psi. I can't think of what it could be. I'm gonna take a look under it tomorrow as its too dark to do it tonight. Any ideas on what I should be looking for?