Weird bleeding

I’m currently in the Dr. office. I had taken plan B in October during the 2nd week. Now I have weird bleeding on last weeks into November. I also started birth control in last weeks. I took a test and it was negative. I want to know if it’s chlyamidia or gonarreah but they insisted on a pregnancy test.

Also I’ve been bleeding now for 2 weeks. Dark blood with cramping. Anybody else ever experience this? It could be my hormones off wack.