Sharp pains during first trimester

This morning I started getting some tight "pulling" sensations in both side of my pelvic area. Not constantly, mainly when I stretch or change from sitting to standing. It's not unbearable. No bleeding or spotting. I'm not sure if this is just a normal part of everything stretching or to call OB? I'm thinking I'm ever 6 or 5 weeks along - not totally sure as I had bleeding that my OB thinks may have been implantation bleeding that was similar to a whole period for me. I've only had 1 hcg done and no ultrasounds yet - not even scheduled for an appt until my HCG hits 1000.