Painful sex

A few days ago, I was on my back and it felt like with every thrust he was hitting a wall of nerves. The next time we had sex it was doggy style and I couldn't feel the wall but he said he could. Then this last time I was on my back again and the wall felt like it was tighter. It hurt like a mother and after I had a shooting pain down my right leg. This past week was my fertile window according to this app and it says I should expect my period on the 31st. Almost my entire fertile window I spent having unprotected sex with my partner. So whats up with the wall? Any sort of answer would be nice. Please and thank you.