Black blood for a week and a half?


Hi all, I'm made this post because I'm starting to get nervous. I've been having brown/black discharge for like a week and a half now. The week before my period started I had very light brown spotting, now its moved into my period week and I'm having this darker black discharge but still not my normal period at all. I'm not sure what's going on and I my Gyno can't fit me in until January. Can someone help??