My last period was 13th May and not due for two weeks according to glow, however, I have been using cerazette (with a few missed) and unprotected sex, but taken the pill when I've remembered, basically I've been spotting for 4 days now but not developing into period, I've taken a test which came back negative but have been experiencing backache, sore breasts, headaches and really bad extreme tiredness.... Do you think it could be period coming early or implantation?!?! Please help the wait is driving me mad!!