Extending cycles with the
pill to this extent can often lead to breakthrough bleeding, which may well render a woman
niddah. Additionally, any changes in pill taking should be discussed with a physician.
In your case, if you wiped yourself with tissues or toilet paper after at least fifteen seconds had elapsed from withdrawal, then what you found could be disregarded as a stain on a surface that does not render women
niddah. See our pages on
stains and
toilet paper for more details.
If you found the stains on a white cloth, then your status depends on the exact shade of brown. Dark browns sometimes do render a woman
niddah, although a halachic authority could
evaluate the stain and might be lenient.
If you found the stains within fifteen seconds after intercourse, on any type of surface, a halachic authority should definitely be consulted as there is a particular concern about
blood found after relations.