Rear end

Sounds like you have an automatic load-leveling system. There will either be a height sensor in one of the rear struts or there will be a sensor on the body underneath with a link connected to the suspension system. That link may have become disconnected. If the sensor falls to the "low" position, the system will keep trying to raise the back of the car. A much less common problem occurs when a strut is fully extended then sticks in that position. Typically this only happens when the car is raised on a hoist allowing the suspension to drop fully. The strut will usually release at some point while you're driving but it can be real uncomfortable until that happens. The fix for that is to replace both struts although that might not occur again until the next time the car is raised on a hoist.