So if I have regular period where they start light get into medium/heavy flow and towards the end it lightens up almost every period . Now this month I got one started Tuesday and by fri (today) it's just brown meaning old blood and stayed light, so light hardly filled a light tampon . Could their be a chance maybe I am pregnant just not showing positive yet and my body could be adjusting . Or maybe implantation it stayed between brown and very pink I think one day had very little red but that's only day it was seen?