hi. i had a similar experience when i was pregnant with my daughter. i went to the hospital for cramping/lower back pain. they saw the yolk sac but no baby or heart beat. i went to my ob/gyn 2 weeks later and they said that the fetus won't have a heartbeat until the 8-9 week mark. and by then movement may also be seen. needless to say my daughter is now 6 months old and very healthy! don't worry. i am sure your baby is fine! congratulations!
is it normal to not see a heart beat or movement on an ultrasound around the 6-7 week mark?