Diagnosing fish is always hard to do. She might just be constipated--in which case don't feed her for a couple of days and then only feed her small amounts (perhaps more often throughout the day) and she should recover. Some people say a boiled green pea (smushed up) fed to her helps.
She may be egg bound. If so, if she doesn't mate to get rid of the eggs, she'll either reabsorb the eggs and be fine, drop the unfertlized eggs and be fine or die.
But, she might have dropsy, especially since she won't eat. Dropsy is almost always fatal, especially when they stop eating. It is internal, so the kidneys and things get infected so they no longer work and the fish retains liquids (thus the bloating). If you can catch it in it's early stages, you can try feeding your fish antibiotics so the med gets inside where it can do some good, and then also use an antibiotic in the water (Kanacyn is good since it's suppose to be absorbed through the skin). However, I've never been able to save a fish that has dropsy. If her scales start sticking out, it's definitely dropsy but dropsy doesn't always make the scales bristle outwards.
