Period 1 week early???

So this am, i woke up very crampy and when i went to potty and wiped there was light blood on the tissue. Since then ive been even more crampy/nauseous. I am not due for my period for at least another week. We did have sex according to when glow said i was fertile, which was between 9 to 11 days ago! I haven't been stressed or anything , if anything im less stressed than ever! Has anyone had this happened to them? Thanks for the info yal!!