Yesterday my GF had to ask me to stop fucking her for a few minutes. She said it felt like I had hit her spine from the inside. I was momentarily frightened out of my wits and of course I quit immediately, but I wondered what was going on anatomically that could have caused her to have this kind of pain. She said it was different from a regular back spasm, because it felt like it emanated from the inside. It subsided after a few minutes, too, which gave me a lot of relief. Could it just be a result of repeated pounding on the back wall of her vagina? I bottom out with about an inch to spare with her, but I think her vagina was fully tented and I was only hitting at the top, not at the dorsal wall. She's had a partial hysterectomy, so I wasn't beating her womb or cervix. She's still in possession of her ovaries (God bless 'em), so she makes plenty of natural lubricant. She's probably the wettest woman I've ever been with, and does FE on occasion. Has anybody experienced this before? She sure is a sweetie and I hate the idea of hurting her at all by accident. Now, doing it on purpose on demand is another story. I don't know if it's relevant, but I'm 8X6. Not huge, but I'm hoping I'm not big enough to do her any real injury. Please share your experiences with me.