Old blood

I’m about 6 weeks pregnant and I’m having some dark brown bleeding like( looks like when you just ended your period, that dark brown stuff) my levels Sunday we’re 538 and yesterday they were 1,309. I possibly go for another beta tomorrow and ultrasound. I had to put a panty liner from how much Was coming out but I’ve had No cramping. Any ideas? Google gives the worst answers 😣 I won’t be using that anymore