Birth control and periods

So I’ve been started on birth control pills for two weeks now and my period usually wouldn’t be due for another week. I know the hormones in the pill can effect things like that but when I got it this morning, it wasn’t like a normal period. I went to pee and the blood was very very dark, like black. And it wasn’t the consistency it usually is. It was more thick and it kinda had stringy stuff going on. I looked it up and I can’t find anything on it. Anybody know what’s going on???