So i had unprotected sex and i have been having signs of pregnancy, i took Plan B, but I know its not 100% effective and i waited almost 3 days to take it. I started having hot flashes about 4 days ago and that kind of hit me in the face like wow i think i might be pregnant. The other day i got out of class and went to the bathroom and there was light pink blood on the toliet paper. An hour later i went to change the Tampon and it was brown. and by the next day it was gone. Does that sound like Implantation bleeding!?