For the past week, I have heard a bump in the back of my car. For example, I will go over a speed bump, and I hear this thing hit the bottom of my car. It sounds like its a little behind the rear passenger seats. So, I get out of the car today, and I pushed the car down from the back. I hear it, and I can hear liquid moving in a tank and also something is sqeaking. Some people have told me it is the rear shock mounts, however I have no idea what those are and how to fix it. Any help is appreciated.