Ultra sound today

So we went in for our first ultra sound today. I started bleeding last night so they wanted me to come in to check me out... Gestational sac and yoke but no baby or heart beat! I panicked!! I will be 8 was tomorrow. They told me this happens sometimes. Has anyone else experienced this? They want me to come back in a week to see if they can see any growth or anything different. I am still bleeding almost like a light period. Any tips, info, or advice is much appreciated!