Here is another good article about egg binding from the Chicken Chick. http://www.the-chicken-chick.com/2012/07/chicken-egg-binding-causes-symptoms.html
If there is a hard shell egg in there you should be able to feel it without having to examine her vent internally. Just gently squeeze her below the vent with one hand like you are squeezing a child's cheeks (quoting the Chicken Chick) and if there is an egg in there you should be able to feel it. If you feel an egg you can give her calcium and a warm bath to encourage her to lay. The Chicken Chick article gives you all of the particulars.
I know you said she is not eating, but is she not drinking as well?
If there is a hard shell egg in there you should be able to feel it without having to examine her vent internally. Just gently squeeze her below the vent with one hand like you are squeezing a child's cheeks (quoting the Chicken Chick) and if there is an egg in there you should be able to feel it. If you feel an egg you can give her calcium and a warm bath to encourage her to lay. The Chicken Chick article gives you all of the particulars.
I know you said she is not eating, but is she not drinking as well?
Your girl might be genetically predisposed to having laying issues. Just like 3goodeggs said it is a shame they cannot tell us what is wrong. Please read those two articles I posted if you haven't already, they are full of good info that might help her.
