i'm going to say it might be related to the inferior dog bone design, depending on speed of decelleration. basically the dog bone makes the wheels spin instead of the engine.. but then when you transfer that torque, having the wheels spin the to slow the engine, the engine rocks the other way.. the aveo dog bone allows quite a bit (too much) movement. But there as a lot of pieces in there the should not have worn out yet that could cause your symptoms. An unbalanced wheel would get worse with speed more so that just while decellerating. (which i think you already suspect.)

The creaking is most likely your swaybar. But there have been a few instances of rear beam bushings failing prematurely as well.