Pregnancy and Endometriosis

I have severe endometriosis with ovarian cysts and a titled uterus. My husband and I started TTC in early February. I had a positive pregnancy test a week ago and called my doctor to make an appointment. This past Monday I had some rose gold colored spotting so I called my doctor again and they told me to come in. They did a transvaginal ultrasound and they found that my gestational sac is elongated and there was also a yolk sac but there wasn’t a baby in the sac at all. The doctor was concerned because of my irregular sac and because I was spotting. They said I was probably around 5 weeks. They said that it could be too early or it has already stopped development and that I should prepare myself to look for signs of miscarriage. They told me to come back in a week which will be this coming Tuesday and they will do another ultrasound to see if a baby has developed. If our baby hasn’t developed by then they said that they’ll have to rule it as a miscarriage. Since this past Monday I have not stopped spotting and the blood has changed colors from rose gold to dark brown and I have been having back pain and bad abdominal cramps. Has anyone that has endometriosis experienced this? Is the spotting and cramping normal? I thought it could be implantation bleeding but it’s been going on for almost a week now so I don’t think that’s it. It’s not heavy at all and it’s only when I wipe. Could that still be a miscarriage? It’s so hard to tell the difference since my body is always doing crazy things because of my endo. I feel like I’m going crazy waiting on Tuesday to get here!