it sounds like it is early 4-5 weeks so yeah a scan wouldnt show anything and it ties in with the brown blood which is a sign of old blood and usually connected to an implantation bleed (where little embryo snuggles in nice and deep into your uterus). any bleeding is scary for a Mama, but the brown stuff is usually the ok stuff! i had brown spotting/bleeding with 2 out of 3 of my successful pregnancies in the 4-5 week pregnant mark.

there is also a chance of breakthrough bleeding which generally occurs once a month for a couple months after conception (ties in with your regular AF cycle). this too is normal!

Goodluck for the upcoming weeks and scans and wishing you a happy pregnancy and beyond!