Salmon is fine, just to see if she will eat. Hopefully, it is just something harmless. I have had hens start to lay, and then become broody. Keep us informed on how she is doing.
Welcome to BYC. I would put on a rubber glove, then insert one finger inside the vent 1-2 inches to check for a stuck egg. Give her a calcium tablet, Tums, or other form of calcium. If you feel an egg, then place her in a shallow warm bath up to the bottom of her wings. Massage her belly toward...