Yo, is this weird?

So, I had to take Plan B around 5-6 days ago (around day 11 of my cycle; <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">eve</a> said my fertile window wasn’t until day 16-22 because I have a longer cycle, and I know I wasn’t ovulating). And last night, I had little bits of brown blood coming out (not enough for a liner. Very light in color). But I decided to go ahead and wear a liner, and when I woke up this morning, there was a huge blob of brownish-dark red blood, and it felt like it was running out of me. I have also had a big increase of vitamin C intake recently. I was wondering if anyone has any comments or advice or something? Because I’ve never had this before.

Update: I have begun cramping and have a serious headache. I’ve had to change to a pad instead of a liner, and I have quarter-sized blood clots coming out.