I would definately candle the eggs to see if there is anything going on in there. All the temp fluctuations worries me a bit but anything is possible. My broody hen got off her nest on a daily basis but not for long periods of time. ANother broody i had got off her nest and a roo got in and buried her eggs, for hours they were buried, one egg hatched the others didn't. I hope these lil peeps make it for you.