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Looks like a prolapse.
If you are not sure if she laid an egg or not, put on a glove lubricated with a bit of ky jelly or coconut oil and feel inside about an inch and see if there is an egg.
For treatment of the prolapse you will want to clean the area really well and use hemmoroid cream or honey and gently push the prolapse back in.
Do you feed layer feed and offer oyster shells free choice?
Here's a bit more detail about prolapse treatment and egg quality problems:
Edited by Wyorp Rock - 3/6/16 at 8:20pm