My Bf and I had unprotected sex on a Saturday and Sunday then went to get the plan b. I am on bc but was in the middle of changing types..a week later I had what seemed like a normal early period.. I bled for four to five days and then stopped... A week after I started bleeding again.. With cramps and really tender breast.. But this one came when my normal cycle is (the 3rd-4th) why am I bleeding again if I'm not pregnant??