Spotting 7 Days before AF Due

Katie
Hello all. I started spotting at 7dpo. This has continued for four days. I've never had this before. I don't believe it's inplantation since it's lasted this long. Are there other causes that cause this type of passive/mild blood loss?
Slight TMI
To clarify; the spotting is only when wiping after using the bathroom. It has happened only once per day. Then it stops and there's no sign. The next day there is a small amount of blood on the paper. Then nothing for the rest of the day. And so on. 
AF is due in 5 days (happy new year to me lol).  
Any insight or causes I can look up? Thank you.