TL;DR - Internal/Female Condoms can cause pain if the inside ring gets pushed too deep in your vagina.
So about two years ago, I started becoming sexually active with my wonderful boyfriend. Due to complications with other regular condoms, we had to use internal condoms. I noticed that every time I had sex, it would hurt. It would be difficult for him to get in since my vagina would be really tight and it would also hurt if he went too deep. I scoured the internet for answers, but I didn't seem to get anything other than the normal "sex shouldn't hurt and if it does, there's something medically wrong." However, a couple days ago, I learned the answer via unprotected sex*.
I noticed that when I had unprotected sex, my natural lubricants didn't close up my vagina and make it tight and when my boyfriend went deeper, it didn't hurt. After switching back to the condom halfway during sex, the lubricant that is already present on the condom made my vagina tight again and the ring started to hurt while it was being pushed too far.
Hopefully this helps other people. I also hope this doesn't scare people away from internal condoms. Just because they negatively affect my body, doesn't mean it'll negatively affect yours.
*(Disclaimer: I'm on birth control and him and I get tested regularly. Don't worry )