g4wam

I am looking for any ideas on the following self inflicted problem.

I made a mistake of driving down a farm track , couldn't get far down and had to reverse back up to the main road. Unfortunately I didn't notice a large crater at the end of the farm tack where it joined the road and my rear offside wheel fell into it and made a loud noise, Since then I get a horrible creaking noise when I reverse while braking ( suspension dipping) . I jacked up the rear to investigate and removed the rear wheels and put another jack under the rear offside hub area and raised the suspension and it creaks quite loudly on dropping down .Tried the same on the rear n/s and it is creak free. The noise appears to come from above the lower suspension area.
any ideas welcome

Mike