Brown Spotting

I've had spotting since 9dpo. I was sure my period was coming then it went away to just light brown discharge. I got my BFP at 15 dpo and haven't stopped having that brown discharge. I've had a little cramping but nothing severe. I'm getting my blood hcg levels tested and go in tomorrow to see what they are doing.

Does anyone have any experience with this? Any help would be appreciated!