Hi there,
Sounds familiar to what happened with me last year. I had day 5 blast transfered and 1 week later had pink spotting and mucus, turned out to be implantation bleed. I was on 3 perssaries a day and hadnt had that before. That was my 3rd ICSI transfer and had 5 x FET. Just finished 4th ICSI and same thing happened this time. Hoping for the same outcome as last one ended with D&C

Hope yours is implantation bleed, all the best xxx