Your body is producing a hormone called relaxin. This hormone loosens all your joints. It is often very painful in your pubic bone usually when you turn over in bed or get into/out of a car. Your pubic bone is actually 2 bones joined in the middle. This joint does not usually move however under the influence of relaxin this joint often moves. When this happens these 2 bones rub together every time you move causing the pain you are feeling.