7 weeks slow heart rate and large yolk sac

Hi ladies

So I had a scan and I am just over 7 weeks. At the start of the scan the fetal heart rate was 110 but as the scan went on it dropped to 90. The doctor also said I had a large yolk sac - over 6mm and can be linked to miscarriage.

I had a scan only a few days prior and the yolk was a normal 3.9mm.

So my question is - has anyone had a yolk sac grow that quickly?

Has anyone also had the heart rate increase by the next scan?

I am absolutely devastated that it probably will be a miscarriage. I had a miscarriage last year and not sure how I will survive it.

Any advice would help?

Thank you x