A lash egg is not an egg, it's a mass of infectious material, ie: pus. It's caused by salpingitis. Some masses are small and can be passed, some are large, or long and tubular shaped and can fill and block the oviduct. It can sometimes cause a prolapse if the chicken is trying to expel it, and it can block her from being able to expel droppings.
I can't tell if that's what's going on or not, but something to consider.
https://the-chicken-chick.com/salpingitis-lash-eggs-in-backyard/
https://the-chicken-chick.com/causes-of-lash-eggs-salpingitis-by/
I would give her only water soluble foods, her regular feed mixed with water to make a mash, make sure she's getting plenty of fluids, and give her some coconut oil to help lubricate things in case it's constipation. A couple of teaspoons of coconut oil, you can freeze it til firm and break it into peices and she will probably eat it, they usually like it. Or you can put bits in her beak and she will swallow it. Do that a couple times a day, and see if it helps. You can also repeat the soaks and oil around the vent, and inside the edge as much as you can to see if it helps soften it and lets her pass whatever it is.