TMI need help

I was supposed to start my period on the 4th but it didn't come. On the 7th I started getting the dark brown blood so I thought it was just my period starting. Today's the 11th and I'm still getting just the "old blood" but it's really dark like basically black and it's not really a lot except for when I wipe myself. I can tell it's the lining of my uterus because it looks like strings of skin, but why isn't it normal blood? Is this normal for it to still be dark?