Feel inside her vent an inch or two with one finger, and if she is egg bound you may feel the egg. Make sure that she is drinking plenty of water, and give her some extra calcium one time--either a calcium tablet, a Tums, or grind up some egg shells and give in some yogurt. There are many other illnesses besides egg binding that could cause these symptoms. Look her skin over around the vent, under wings, and the neck for tiny lice or mites. Feel of her crop, and describe if it is full and hard or soft, or empty. Add electrolytes her water and offer some chopped egg or tuna. By all means, if nothing seems to add up, a vet would be helpful. Heart, liver, or kidney disease, internal laying or egg yolk peritonitis, and coccidiosis are some of the common problems in chickens. What color is her poop? Here are a couple of articles to read:
http://www.the-chicken-chick.com/2012/07/chicken-egg-binding-causes-symptoms.html
https://www.beautyofbirds.com/eggbinding.html
http://scoopfromthecoop.nutrenaworld.com/tag/laying-issues/