I know what the problem is, it's that she's fat. I had this problem with a juvenile ball python that was eating regular adult mice at the time which gave him a good little bulge. Well I fed him a small rat which was at least twice his size because that's all I had at that time and after three or four days of digesting I noticed the same thing. It's that extra bulge of soft tissue from about and inch or so from the tip of the tail to where the neck starts. This is what fat looks like on a snake. I waited until a week after I fed him and he was slimmed down some, and then I waited another week and he was back to his normal self. Basically don't feed her again until she's back to normal. After that either feed her a smaller meal or feed her every two weeks. Hope this helps.