I have been on birth control for years and never had any problems. Now all of a sudden when I urinate and wipe, there is a trace of blood on the toilet paper. It s not alot and not everytime, very sporadic but I m wonderin what it is from. I took a pregnancy test and it was negative. I m only seeing the blood when I wipe and It s not all the time and not only when my period is due but just all month long. but I m wondering what is the cause? Do I need to switch birth control?