Distinguishing between period/miscarriage and bleeding in early pregnancy

[Anotheronemaybe]

Sorry to put this here but the pregnancy forum isn't very busy. Found out I was pregnant on Monday and would guess myself about 5 weeks. I have children but a history of miscarriages- two silent where they had died around 8 weeks. I started to bleed some dark blood on Tuesday night, it stopped, I called the Early Pregnancy Unit and they have arranged a scan for late next week. I've been spotting brown stuff every day. Last night, had stomach pain and the blood was fresh. Today I've filled a sanitary towel and starting to think it's just my period.
Does anyone have any experience of this? The timing of the baby isn't ideal but I'm disappointed.