What Causes Periods Like Bleeding 3 Weeks After An Operation?

I AM LITTLE OVER 3 WEEKS POST-OP. STARTED BLEEDING AT 2 WEEKS (ALL BLEEDING HAD STOPPED DAYS PRIOR TO THAT. FOR 5 DAYS IT WAS LIKE A PERIOD, FILLING ABOUT 2/3 PAD EVERY HOUR. FOR THE PAST 5 DAYS SINCE, IT IS LESS BUT STILL ABOUT A QUARTER OR THIRD OF A PAD. DOCTOR HAS EXAMINED ME & SAYS CUFF IS OK. SHE JUST KEEPS SAYING ABDOMINAL BLOOD & FLUIDS ARE SEEPING INTO MY VAGINA BETWEEN STITCHES. BUT THIS IS NOT SEEPING RATE TO ME. I DON T UNDERSTAND WHERE THE BLOOD IS COMING FROM, HOW IT IS GETTING IN, & WHY IT CONTINUES TO FLOW.