They often lift off or get off the eggs when temps are that high to moderate the egg temps so don't panic. Keeping cool water in her waterer will help her. If you have a sand bath ( like a concrete mixing tub or the like) you can damp some potting soil and let her "bathe". It does help cool and adds humidity to her feathers.
This time of year I actually just run water for the chickens since we're on a well, I run it constantly into a shallow dish and coming from the aquifer it's quite cool. They really seem to appreciate it - silly things will stand in it for a bit, even the tinies. Fortunately since it is constantly refreshing, no mess stays in the dish. Would cost me a small fortune on town water. I love my well.
we have a well also i have a bird bath on the ground tilted so it does the samething and run drips from 10 am to 6pm everyday they love it under all the bushes.