Pain from air pressure?

Hi everyone, new member here... I've been searching around and didn't really come across anything about this, so I thought I would ask it here.

I don't bottom very frequently, though I would like to do it more. Aside from the pain from my tight hole being stretched open which I'm learning to manage better, there's a different pain that I experience.

It feels like there's air inside that's being pushed in by the penis, but that air has nowhere to go inside, so it ends up stretching my (colon?) like a balloon being blown up.

I'm not sure if it's air trapped between the first and second sphincter rings? Or if it's air at all, or if the penis is pushing on something? All I know is it's not a comfortable pain.

Once he pulls out everything is fine again. It only happens when the guy is trying to push it deep. And it seems to happen only when I'm on my back. The guys I've been with are not particularly big... they're around average size, like 6 or 6.5". Guys with bigger penises I pretty much tell them I won't/can't.

Does anyone have any idea on what I'm talking about, and perhaps suggestions on what I can try? Thank you!

Phil, that makes sense... Any suggestions if the guy is indeed pushing on the colon tissues on how to avoid that? Is it just a matter of positioning?

I'd rather not give up bottoming since I enjoy it when it's not painful... The problem is it's not always not painful, and it's disappointing to the top when I can only bottom for about a minute or two before I tell him I can't do it anymore. I'm trying to learn to be better at it...