Why is my rabbit's belly so big?

My rabbit’s belly has been looking bigger than normal for a few days now. It shrinks a little but gets bigger again after she eats. She seems fine otherwise—she runs, jumps, eats, drinks, and uses the bathroom like normal. Her appetite is huge, and her belly feels firm but a bit squishy. Could she just be gaining weight, or is there something else going on? Please, any advice would help.

It might be gas or even the early stages of GI stasis, which can be very dangerous for rabbits. Does she always have access to hay? Try giving only hay for now (Timothy hay, not alfalfa) and see if it helps. Watch her closely, especially her poop. If she stops pooping, you need to get her to a vet quickly. GI stasis can turn serious fast.

@Dane
She’s still pooping, peeing, eating, and drinking just fine. But when I pick her up, I can hear liquid sounds in her belly, like something sloshing around. Is that normal?