Ok ladies need some help please tmi

I’m 26+2 days pregnant with my second and up until now I’ve had constipation but the past 3 days I’ve had diarrhea with some blood, blackish colored chunks and mucus in it. This diarrhea is accompanied by back pain and stomach cramping/hardening. I have not changed anything in my diet recently. I’m starting to worry because I never had this with my daughter. Any advice would be helpful. Thanks in advance.