17 weeks

I'm currently 17 weeks and for about a week I've had this "pressure" that's right at the top of my pubic bone. It almost feels as If the baby is in a ball and just staying there. It happens most when I am sitting for a period of time or standing too long. Laying down the feeling goes away. It lasts too long for me to consider it as contractions I feel. Just curious if this is a normal feeling or if I need to call my OB asap.