Just as you thought you have said goodbye to the unforgettable memory of childbirth. The pain of contractions silently creeps back to you especially while you are nursing. What you are experiencing are afterpains, which helps your uterus shrinks back to its normal size after child bearing.
You can probably feel the afterpains more intensely if it is your subsequent pregnancy since your uterine muscles are more likely to be lacking in tone due to stretching from previous births. Painkillers can be taken if prescribed by your practitioner.