Placenta parts left

knottie9a164e2053832c35

Hello, I don’t know if this is the right place to post this but has anyone had placenta parts left behind? I am just over 8 weeks postpartum. I am still bleeding lightly but enough that I still need a tampon. It has hurt to put a tampon in or to have sex. Could that be because I have parts of placenta left that is causing the pain? I go for my ultrasound tomorrow. What is the surgery like if I need it? What is the recovery time?
Thank you In advance.