Nissan Repair: flapping noise, discrepancies, what the heck

Question
My question isn't so technical or specific.  I'm grasping at anything to figure out what the heck is going on.  I have an 07 with 12,000 miles on it.  Recently, I've noticed a flapping noise when I drive.  It sounds like something is hitting very rapidly near the rear right tire. I have absolutely no clue what it could be.  Any thoughts or help finding out would be helpful and appreciated.  Thanks.

Answer
Hi Paul -

I assume you have looked under the car and found no discrepancies -

try this - check between the treads of the rear right tire. Sometimes you pick up a rock or nail that wedges between the treads, and the part that sticks out hits the pavement every time the tire makes a rotation. This could cause that flapping noise.

Hope this helps -
aloha
calvin