This is a 6 month old 2018 pilot that suddenly started making this knocking noise from rear drivers side when the car sways side to side, makes turns or slows and speeds up. This is heard only at lower speeds not on the highway and is not a steady noise but often enough to be annoying. Also loud enough that it may be coming from inside rear and not under the car. We have removed all personal items from trunk area including the trunk cover. Nothing in the back except original car as the day it was purchased but obviously something changed in the past month. The question is what???