It's really scary isn't it - you just can't help thinking the worst.
I had bleeding throughout my pg with ds - from about 6 weeks, and a couple of instances with dd. Mostly brown blood (which essentially says it's 'old' blood', but also pink (less old) and quite a bit of fresh red spotting at various points. With ds (my first), we ended up in the EPU at 6 weeks, 7 weeks & 8 weeks ... at which point they told me not to come back in unless something impressive happened . I think the longest I went in that pg without a bleed was 3 weeks. Usually I bled about twice a week. Various things were diagnosed, then discounted - but tbh one mw told me that actuially they don't get to the bottom of most pg bleeds.
(I was also told when I had my scans that if they could detect a heartbeat early (it isn't always possible) - that's a good sign.)
Oh, and ds is fine - arrived 4 weeks early, but otherwise as normal as any other 3 1/2 yo...
So is dd - who arrived 2 days after her due date.
Someone told me that about 1/3 of pg women bleed at some point - most in the first trimester, so consider yourself in good company! Of course, some of those end badly, but by no means all of them.
Good luck with the rest of your pg - fingers crossed that this is a one off for you.