I had my period on the 14th of this month and it ended on the 17th which is pretty normal for me. It is always a little heavy at first but gets really light towards the end. Well before I started my period me and my boyfriend of 3 years have had unprotected sex, which is something we've always done. & he ejaculates inside of me every time. I have Cystic Fibrosis so it's harder for me to conceive but I am concerned because I started what seems like my period again today (the 20th). What could be the cause of this??