TMI pic in comments

So I started my period on time, 2 days ago, the first day I was bleeding abnormally heavy. I'm talking soaking a super plus tampon and pad within 45 minutes so needless to say, I went through a good majority of my pads and tampons off the bat and bled through 3 pairs of pants and panties. My boyfriend brought me home a diva cup because I somehow lost mine (really sweet of him to do) which has helped a lot. I've noticed larger than average clots as well. Well I checked my cup and the blood is weird. So as you can see bright red blood, then there's dark red and black blood in the cup as well as some gray blood. The gray and black blood concern me because I've never had gray or black blood come out before. Nothing about this period has been normal. I don't even think I bled this heavy after I gave birth. Could this be a missed pregnancy? Or maybe my antibiotics changed my blood? I've been on Doxycycline for an unspecified acute lower respiratory infection for 7 days now. That's the only thing that has changed within this cycle.