No I'm not sure, esp. since this is our first time with chickens let alone a prolapse. I am thinking there isn't an egg though, because we got the usual amount of eggs and actually one more each day lately so I'm pretty sure she laid an egg the morning this happened.
If she's egg bound would I see an egg shape? There isn't a shape like that, and you can gently feel that it's more like tissue, not an egg.