Puppy won't stop eating her sh*t?

Why is my 14 week APBT eating her sh*t?...She will finish the entire thing if I don't catch her and it's f*cking gross since her sh*t reeks like hell then she comes and licks my face. I feed her blue buffalo and she stopped for a while but now she's doing it again. -_- How can I get her to stop? I feed her enough, 1 cup 3x a day.