Unusual bleeding after sex...

Hi hi. I had to have a D&C on February 18th due to a miscarriage. My husband and I are trying again, but have run into some road blocks. About 3 months after the D&C, I began to bleed (similar to a light period) a day or so after we had sex. Usually the bleeding only lasts about a day or so. I have never bled after sex and thought it was weird that it started a day after we had sex. When I called my doctor, he scheduled for me to have an ultrasound and a biopsy. Has anyone else experienced this? Trying to stay positive, but I dont go to the doctor for another 2 weeks.