Why is my right testicle riding up?

I have (with much distress) that sometimes when I am having intercourse with my girlfriend, at the point of climax, my right testicle will "ride up" out of the scrotum into my body. I can feel it wedged up there and I usually can push it out back into the scrotum after withdrawal. Is this something I should be worried about?!!! I was born with normally descended testicles, and I haven't been kicked in the groin or anything and it only happens sometimes, not every time. It doesn't hurt when it rides up, but it is uncomfortable and feels strange. It is only the right one, never the left that does this.


Is it possible to penetrate the cervix?

I've read some other questions on here about men hitting the cervix with their penis and that the penis doesn't go through the cervix. I'm larger than average and my girlfriend is telling me that I'm actually going through the cervix. When we first started having sex it was very painful for her because she thought that I was penetrating the cervix. Now she's past it being painful but still thinks that I'm actually penetrating the cervix. My question is, is that possible?