Chemical pregnancy ??

I’m wondering if I’m having a chemical pregnancy??? Back story I went to the doctors because I didn’t have a cycle for two months. Doctor started me on medicine to start my cycle.. come to find out I was pregnant the whole time taking the medicine. I’ve been bleeding for a week and had and ultrasound.. (not full period but spotting and now a little darker) on the ultrasound there’s a sac but no egg yet.. which would be right because it would be too early.. however I’m still bleeding and I’m scared I’m loosing the baby because I took the medicine unknowing I was pregnant already. I’m still getting dark pregnancy test though so idk… chemical or implantation?? I did have bleeding with my son the first week I found out but not this long..