Hi Scott,
What you're describing sounds very similar to reported cases of the HUB coming loose from the axle which is caused by shot wheel bearings. If the wheel bearing is shot and not replaced it will eventually lead to the HUB separating from the axle and this will cost mega $$$$ to fix as the entire wheel hub assembly will require replacement.
I suggest you take it to independent mechanic who knows about wheel hubs and bearings and get it fixed urgently because this is a very serious fault in terms of safety.
More information about this defect can be found on the Australian Forum
HERE
