Pain during sex

Lately I've been to the doctors regularly for about 8 months.

I've went for bad period pain and struggling to get pregnant.

But the past 2 nights my partner and I have tried to had sex and it was just way to sore. I've never had a problem with being sore before and I'm wondering is it normal?

They think i have endometriosis but I find it strange that it's only been the past 2 nights.