It may be because 1) you are either closer to the subject than the lens’s focal length or 2) the closer that you are, the more prone the picture is to the movement of your hand.

Try and take a picture using the timer function. See if that makes a difference.

also try changing the camera to macro mode (prob a flower symbol) when you want to take close ups. this may help your lens focus on closer objects and it will use the flash to reduce blurriness.