What Causes High Levels Of HCG After Miscarriage?

Hi. I had a BO and miscarriage on Nov. 9th. My husband and I had sex a little over a week after but have not since. My HCG was going down after and was at 2.5 nov. 30th and i went back again yesterday and now it is over 2,000. I am going in to day for an ultrasound. could I actually be pregnant? I also had AGAR? cells, atypical endometiral cells on my cervix, had my cervix and uterus biopsied last Friday. Could cancer increase HCG? I am scared and confused
Thank you