Girls, I'm in the hospital on bed rest; I started bleeding at 8 weeks.…

Girls, I'm in the hospital on bed rest; I started bleeding at 8 weeks. The ultrasound shows two gestational sacs, but no embryos are visible. hCG levels are rising over time. The doctors are puzzled. Has anyone experienced embryos appearing later? I'm so worried — this is a long-awaited pregnancy. I pray to Allah for healthy children ?