Period

I have been taking pills, I started one month ago, and my period was normal, I take a pregnancy test and it was negative, days after it started to have like a little of blood but very dark, know one month after, I should be in my days, but the color of my period is not normal, is like dark and in clots and its like very few, like the days after my period one month ago.. So my question is.. Is this normal? Or could I be pregnant?