Pregnancy Need your advice. Please help?

Last weekend I started getting horrible lower back pains and some cramping. My cycle is always on time give or take. I started on the 21st. Which is on time. But as to where my periods last a full seven days it seems like I'm almost off today (the 24th) and my period was generally light compared to how they usually are. I've had horrible back pain and horrible head aches today. Not to mention the felling I've had in my abdomin, not so much as a sickness feeling but like a erflies feeling and I've been horribly emotional. I'm also just not feeling myself lately. And to add while at the dr a while back I was told the chances of me getting pregnant weren't to likely so me and my fianc� have had unprotected for somewhat 6months and he doesn't pull out.. What advice do you have for me? Did any women out there still have their period during they're early pergnancy? Anything would help. Please be nice. And thank you for your time.