What Cause Sharp Abdominal Pain And Blood Clots Discharge From The Vagina?

Hi, I had a D&C two months back due to a miscarriage at 5 weeks. My first period came a month later, nothing unusual which is the same as all my previous ones. However, 17 days after my period I started to feel sharp abdominal pain followed by bleeding. The following day, my bleeding was so sudden it soaked through my dress. I rushed to the toilet to realise a big lump of blood clot got flushed out. The following days were just spotting but another episode of sudden gush of blood with big clots came 3 days later after the 1st incident. I had sudden bleeding again while showering and another bleeding before bedtime together with discharge of blood clot the same evening. I went to the gynae the following day and she prescribed me norethethisterone to be taken 2x twice a day. 2 days have passed, I m still experiencing sharp pain occasionally and bleeding still but no clot this time round. Please advise what is happening. We did a few rounds of ultrasounds and internal scans but couldn t find anything.