So I was on antibiotics for around 3 weeks and they ended a couple days into my period that ended on the 12. I'm not supposed to get my period for around another 2 weeks and yesterday I noticed brown discharge and I've never had spotting before in my life so this is not normal for me. Today it's getting darker almost black to dark red like old blood mixed with new blood. Maybe my periods starting because the antibiotic made my birth control pill less effective? Any idea about what's happening?