"That's dangerous." Thank you Captain No-Shit. I'm sure I said the exact same line after a similar situation. Don't feel too bad.
This is what happens when you toe too much behind a truck. A centerload hitch would have absorbed some of the motion only because it is mounted directly above the rear axle of the towing vehicle. Don't give people crap about getting a centerload hitch or towing something that seems small using the centerload hitch.