sick rhode island red

My 2 year old Rhode Island Red hadn't laid in almost 4 months and her belly was hard as rock and slightly distended. I brought her in a few months ago and started giving her warm baths and oiling her vent. Then all my girls started molting and in the middle of the molt we moved to a new place. Through all of this she held her own but never laid and her belly never got soft. Today when I picked her up she was breathing hard and eventually was listless and wasn't regaining any perk so after an hour or so of nothing we dispatched her. Any ideas of what could have been wrong with her? I thought egg bound, but she lasted for so many months that now I'm not sure. Does anyone have any ideas. So sad because this is the first baby I've lost.
Thanks....