Dark brown/ red spotting after ultrasound is this normal?

Britney • I'm a happily married to the love of my life and I'm a 27 year old who is graduating university soon this year and is hoping to start having some beautiful babies soon! We have had one pregnancy and miscarriage at 7 weeks so far hoping for a rainbow baby
I have already been checked out for spotting and he thinks its OK I'm just worried because this is more dark red but only some on a tissue when I wipe not enough for a party liner or anything pls help! I'm also a negative blood type so the doc thinks that is causing the spotting I'm just worried about the colour is this ok or should I go back to the hospital?