NEED ADVICE

I am currently 6 weeks and 1 day pregnant, I had an IUI on 8/8/17 conceived in 8/14 I had an ultrasound starting at 5 weeks because I have a history of miscarriages, I went I for my first one at 5 weeks and everything looked good you could see the gestational sac measuring at 5 weeks and start of yolk sac and a black spot where they thought baby was, I went back in today for a week follow up on ultrasound at 6 weeks and the tech was showing me where baby was you could see it and flicker of heart beat just wasn't strong enough yet only being 6 weeks, she said everything looked good. I then get a call from my doctor saying that my gestational sac hadn't grown any since last visit and there was no fetal pole seen and I needed to do blood work and come in for an urgent appointment Monday afternoon to discuss options on what could be going on, i've went through 3 miscarriages and know what my options are at this point. is this something I should be worrying about or just wait it out and see what happens.