Could be something so simple as the bush failed or could be a bigger issue. Dare say you will have to start pulling things apart to try to figure out whats what .
Sorry cant be more helpful. Could even be a busted spring
I will try and get the missus to take a picture for me when she gets home the springs are good they are only a couple of thousand kms old it is just the inside of the rear shackle rubbing (only just)on the inside bottom corner of the chassis.