Ovulation or Implantation?

Hey guys,
I'm wondering if it's possible for ovulation spotting to turn into implantation bleeding with very little time in between? I normally experience spotting directly after ovulation (usually starts in the middle of the night on the day of ovulation or the following day) and lasts 2-4 days. And now I'm experiencing brown spotting (7 days post Ovu.) 
So I've been spotting for a total of 5 days! Has this happened to anyone else? AF is due in 4 days but the wait is killing me!