While driving at about 50 mph, I hit a bump on paved highway, vehicle started to vibrate violently. Dropped speed to 40 mph. Vibration continued for two miles, at which time I arrived at my exit on the road. Slowed down to stop for exit and vibration stopped. Made my turn and continued home at about 35 mph. Vibration did not come back, about two miles from exit on highway to my home. I had the front passenger upper ball joint replaced 400 miles ago. I checked the ball joint hardware and everything is tight. The bump in the road was on the front passenger side of vehicle. The vibration seemed to start from the front passenger side of engine or wheel. The steering wheel was shaking vigorously as well as the whole vehicle. Where do I start to look for what is going bad?