This might be a stupid question

I had a D&C in March 2020 due to a miscarriage.

Then another natural miscarriage 2 weeks ago.

Well the last week and a half I’ve had really sharp stabbing pains shooting through my rectum and into my stomach when:

-pushing to poop/urinate

-deep penetration with sex

And just sharp shooting pain in my rectum when:

-cough

-jump

-sit

So I went to my obgyn to see if she could figure out what was going wrong. She stuck two figures in deep into my uterus and I jump because I got that burst of sharp pain that shot from my rectum to my stomach.

Well after that she said well I think you have rectal endometriosis.

What I’m curious about is, if that’s true why wasn’t anything noticed when my D&C was done in March?! Wouldn’t they have seen something while they were in there or on the ultrasounds I had during pregnancy?

Or could I just now be experiencing side effects from my D&C?

I’m just curious why out of no where I have this pain.