Hcg, bleeding, so confused

I started bleeding Monday and it continued until yesterday, I was 5w 4d on monday. I went to my ob and she informed me that my cervix was closed and they did an ultrasound seeing the gestational sac and yolk sac and drew my blood. I went back Wednesday and got a call today with my results. My hcg has gone from 4000 to over 6000. But it's not double. My question is has this happened to anyone else? Heavy bleeding, hcg rising, and not miscarried. I'm still having brown discharge (old blood) any comments are appropriated.