Bleeding in between periods?

About a week ago, I noticed I had a tiny amount of blood in my discharge when I wiped. The next day, I wiped and it was pretty light bleeding, but the whole thing was blood in my discharge. By that night it was gone. Now, a week later, I wiped and discovered some brown blood in my discharge, but not a whole lot. My period is supposed to start Monday. I have been on the same birth control pill, Tri Sprintec, for about 5 years and never had spotting and always have had my period at the exact same time. What could this be? Do I need to change bc pills?