What Does Fluid Collection In Pelvic Area After Having D&C Indicate?

Hello

I underwent D&C hystroscopy on 30th of March.The bleeding was normaL and i wsa very normal for the next 10 days.But two days before,that is my 13th day after D&C i am experiencing un tolerable pain in the pelvic area.It is like a delivery pain.When i rushed to the hospital they took scan and said three is a fluid collection.I dont know what does it mean.Is it normal.Kindly help me.Now i am taking some antibiotics and dolo 650.Is ot ok?please answer my question.