Does Taking Ortho Micronor Cause Light Spotting And Cramps?

I just started ortho micronor (the mini pill) birth control last week. This week, I've spotted lightly for two days and have had cramps and a back ache. It feels like my period but it would be two weeks early. Is this a normal side effect, or should I be concerned? Also, does this spotting mean I am still protected during sex or not?