So, I was due for my period the 1st. End of last month I started spotting brown discharge. That lasted about 4 days. Never turned pink or red. I never needed a pad or even a liner for it. My period has always been regular, but I am now 5 days late. I took a pregnancy test four days ago and it was negative. Can anything else cause the brown spotting and missed period?

*I am having unprotected sex (exclusively with my husband), TTC, I am not stressed, have not lost or gained, is eating well, taking vitamins. I have also had a pap done 3 mos ago, and everything was fine. Can it be anything else? Is it possible to still be pregnant and have a negative, even though my first pregnancy showed psitive on the first day of my missed period?