It's not eggs, it's not constipation, and it isn't dropsy either. I've seen this a few times and posted in an earlier thread about the issue here: http://www.bettafish.com/showthread.php?t=53023
I think you will find it informative. Unfortunately there isn't a cure for a fish that is this advanced. You will just have to watch her for indications that her quality of life has deteriorated to the point that she should be humanely euthanized. If she is having a lot of trouble eating, swimming around, breathing, etc, that time might be really soon. Until then, do what you can to keep her comfortable and make life easier.
Some epsom salt baths may be helpful, but you should expect the bloating to come right back. People (professionals) have tried drawing out the fluid with a syringe--while this did improve the fish's condition temporarily, the bloating just came right back each time. It is probably a consequence of some kind of organ failure.