Spotting 10 days till Week 5

I’ve had light dry brown spotting 4 days before my period was due. I tested positive the day my period was supposed to come. Brown Spotting continued daily till today (10 days since first spotting). I went to A&E today to have it checked out, embryo with yolk sac could be seen within the uterus (hence ruled out ectopic pregnancy). Did a blood test and will redo again in 2 days to check if hCg doubles. I wonder if it’s normal to have brown spotting (no fresh blood streaks), doctor said it’s unusual to have implantation bleeding this long. Appreciate if anyone can share some experiences? Thank you in advance. #advicepls #pleasehelp #firstbaby