Firstly, I get my period every other month, occasionally I pms in between months. I do have sex almost every day with my fiancée, which we rarely use protection for, but avoid him ejaculating inside. We have been for a couple years now. About a week ago I had very small amount of this substance coming out, for about three days. It was just enough to have to use a pantyliner. I was never sure of what it was. It happened around the time between when I would normally get my period, but has never happened before. What could it be? Thank you.

Blood can have that color, if it's old, exposed to air. Old blood can indicate a miscarriage. It is still blood, that came from your uterus probably.

Using the withdrawal method has worked for you for a while but it is really not a method to prevent pregnancy. Get on birth control if you do not wish to become pregnant.

If your next period is late, test for pregnancy. Seeing your OBGyn sooner than your next period would be a good idea.