Check the bearings. If they have slop, it will transfer.
Another is where the plastic cambers connect, a loose screw or an overly used screw hole can cause play. A nut may help if that the case.
I'm curious if your shock shafts are bent, or if the bottom holding part fell off?
Was it taken apart? If it was, is it possible the arms, caster blocks, or stub axle holders were put on the wrong end or side?