It is very, very unlikely you would become pregnant five days before your period is due.
Hormone levels are not high enough to support egg fertilization the week your period is due.
A Period of Wellness, non profit about menstrual cramps, color of menstrual blood and such
http://www.vascular-events.com/fluid.aspx
Its very possible and not to mention the STD"S in this country are very high. Maybe he is manogamous, maybe he isnt but there is no way I would play those kind of risky games in this day in time. You should know better. And being pregnant is something that could be a possibility too and are you ready for a child? Can you afford a child now? You should think about all of this before you do this kind of stuff. No being mean, just getting real!