Sorry you're going through this. To me, it sounds like a missed miscarriage which unfortunately is very common
I found out at my 16wk check up (no issues at all, bleeding, cramping - none of the 'usual' signs) that my son had died almost 1-2wks prior.
I carried him until 17wks, and because my body didn't register his death, had to be induced to have him because I was so far along.
It's normal... Unfortunately...
I had a miscarriage and started to bleed at around 5wks. took me another full 4 weeks to actually miscarry the baby and sac and stuff.
so sorry to hear this though, its hard :(