I very often get cramps within a week before i get my period, and you'll probably experience changes in what you're used to if you've only just begun taking the pill. I highly doubt you're pregnant just because you have an off-colour discharge, it happens to a lot of people. If you're concerned take a test, but discharge is normal a week before getting your period.
it could be the pill, you maybe pregnant. who knows!? TAKE A TEST!