Please help.

Em

My last period was a bit odd. Normally it's a bright or dark red and goes to a light pink or brown by day 6/7. but this time it started off rather dark, and went straight to dark brown from day 4-6 and then light brown. Is this just old blood, or something different? I had a pregnancy scare before this but my period was the correct length and I would say same type of flow. Really don't know what to do.