Thts the vagina wall. I think tht behind it, it's ur G spot or something like tht.
I think I have the same thing. It doesn't hurt it just feels a bit awkward and like something is in the way. I wonder what on earth this is!
I think I may know what it is, it may be the position you are having sex in or how hard you and your partner are doing it. I have felt it once, my boyfriend said it hurt him. He said it felt like I was bending his penis, we were doing it pretty hard so I think that may be it. I hope this helps but it may not, I'm sorry this is all I got.
I know what ur talking about cuz it happens to me all the time with no pain either.