I suffer from Vaginismus, which is an uncontrollable contracting of the vagina, making insertion of anything incredibly painful. Dilation is also a treatment for vaginismus, though I personally have never undergone it.
Good say, I was feeling phantom pains myself reading this lol. I am really glad to be reading this manga though, it is very interesting to have such a frank discussion about these things. Like it doesn't take a rocket science to understand that any surgery (especially involving your below bits) will be rough and painful, but the author has a good way of putting things into perspective while keeping a generally jovial tone.