HELP! Please?!?!

Ok so for the past 3 days I've been getting BFP Today is Day 4 && when I tested this morning I Got A BFP But Started Spotting ;( It's Later In The Day And Now It Looks Like AF Its Not Heavy And I'm Not Cramping Like I Notmally Do When It's Time For AF BUT I Don't Understand Why I Would Get A BFP If AF is here could I still be pregnant?!?! Any advice helps thanks everyone ;)