TMI (no pictures)- what's going on!?

Briana • Boy Girl Twins Born July 2018 at 32 Weeks after TTC since June 2015. MFI and APA syndrome. Had 4 IUIs and IVF fresh transfer prior to FET (2 early miscarriages from IUI and fresh transfer)
Yesterday (Saturday) was 11dpo for me. I wiped around lunch time and had a pink streak. Later that evening I got brown discharge. It got heavier so I thought it was AF but it remained brown overnight with only a speck of red. Only some minor cramping yesterday but nothing bad. As today has progressed it has been very heavy flow (period like) but remained dark brown for the most part. Some small clots but looks like it's just thick/sticky CM. Some red streaks mixed in with CM but it's very thin not really like AF thickness. Cramps feel like more pressure than yesterday. Somewhat nauseous since Friday as well. AF is not due for a couple more days and I'm very regular and it's usually not brown so I'm very confused. Anyone have a clue what is going on!?

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