I believe your describing a situation where the top of the bulkheads want to punch through the ceiling vinylclad metal.
If that is the case, then the basic cause is two fold.
The first is usually caused by towing many miles with improper running gear balance.
The second is caused by axles that have gone bad.
In the first case, severe vibration can cause the shell to flex enough, especially at the wheel area, to cause the top of the bulkheads to punch holes in the ceiling.
In the second case, bad axles will allow the trailer to "bottom out" when hitting bumps, again causing extreme shock to the center as well as the rear end of the trailer.
I would suggest that you also check your trailer for rear end separation, AND, damage to the frame and/or axle mounting plates.
To learn how to check your axles, you can go to our web site, inlandrv.com
Click on articles, then click on the dura-torque axle article.
Perhaps that will answer your questions.