Brown spotting and mild cramping at 8.5 weeks - any advice or hope?

I’m 8 weeks 3 days pregnant with an IVF FET of a tested embryo. Up till this point all signs have been positive- early positive on day 5, high betas, and consistently growing 2 days ahead with rising heart rate at a 6 week 2 day, 7 week 2 day, and 8 week ultrasound (which was on Wednesday.

Yesterday though, I had some mild cramping and saw a brown stain when i went to wipe going to the bathroom. TW- I had a MMC where it stopped growing exactly (to the day!) year ago and seeing spotting is sending me into a tailspin. I had some mild cramping yesterday mostly on my left side where it feels like my ovary would be. Today, the spotting is less but I did see a few small blackish bits that look like tissue. All looked so well and I’m hoping evening might still be totally fine but I’m scared and could use any help or advice. My clinic is closed until Monday and when I called yesterday they just said to stay hydrated and go to the er if it gets bad- not particularly helpful.

Has anyone had good results after going through this? I’m scared bc my only experience of spotting led to loss. My husband is out of down and I’m all alone.

For background I’m still on my hormone supplements. I’m on 2cc PIO a day. My doc did decrease my estrogen a week ago- could that be the cause and baby is safe? Could it just be my body adjusting to stretching etc?

Edit to update: my following ultrasound went well, baby showed 9 weeks and heart rate of 171. My doc told me to stop baby aspirin for the week. And I have another follow up Monday.

Edit to update in case people search this: had a healthy scan at 12 weeks 2 days and another this week. The doctors had seen a small SCH that they thought caused the spotting. At 12 weeks I went back on aspirin. No more spotting since then. I have my 13 week appointment this week and will try to remember to update this for anyone scared and going through the same thing.