Rear Suspension/Struts issue?!
 

Good morning,
I am a new member in this forum.
A few months ago I bought a 2006 Lexus ES330. I has very low mileage for it's age. Only 34K.
In the last few weeks I noticed a strange sound in the back of the car while I drive over a bump or brake hard, it sounds like some thing in banging against the corner / Lower end of the car near / underneath the passenger fender, like some thing is loose. I am a kind of home made mechanic. Fix all my other cars, so I lifted the car and looked underneath, all the bushings and stabilization bars, etc. all looked fine. even when I push on the back corners of the car, I don't hear anything rattling and everything seems to be stable but as soon as I drive over a bump or Brake a little hard, some banging sound comes from underneath the car.
I was wondering if the Struts could be the problem? Although with such low mileage kind of unusual?!
What do you guys think?

Thank you very much for your suggestions.