I would suggest you make a thread in the emergencies/ diseases fourm
https://www.backyardchickens.com/forums/emergencies-diseases-injuries-and-cures.10/
People there might be able to help.
A hen of her age should be getting fed a layer feed of some sort, or a grower feed with a side dish of oyster shells for their calcium needs.
Are you feeding her cooked rice or uncooked rice ?
Make sure you cook it first. If chickens eat dry rice, it will blow up when moisture is introduced and this can cause serious digestive problems.