I re-read my earlier post, I hope you don't think I was chewing you out or anything. It may have sounded harsher than I thought, because I tend be abrupt sometimes, and don't realize how it reads to another person.
They're supposed to get off the nest at least once a day. Mine sometimes charge around like mad little feathered dinosaurs, all fluffed up, growling and barking at anything that comes near them, for anywhere from 10 minutes to half an hour. She might have just been taking her daily break, like she's supposed to, instead of pooping on the eggs again.
Really stinky poo is normal for broodies, it doesn't mean she's got anything wrong with her. they often only poop once a day while brooding, so it's saved up in the gut, fermenting. I know that sounds really gross, but that's how it is!
Eggs aren't nearly as delicate as we think, sometimes. These following examples are cases of "how not to manage your hatching eggs", and not what I'd recommend, but good examples of how tough these eggs can be.
I had a hen on eggs who kept getting confused about which nest was hers. She'd come back from her break, see eggs in a nest, and climb in. Any nest. Her eggs got chilled repeatedly, probably at least 15 times. Other hens were always laying in her nest, and eggs got broken. She started out with, I forget, but 10 or 12, something like that, ended up with only 6. Those 6 had gotten washed every time an egg (or 2) got broken in the nest. The last couple of times I didn't even bother to take them up to the house for warm water, I just washed them off under the cold water at the coop faucet. By then, I didn't think these would hatch anyway, and was just leaving them as "place-holders", waiting for the hen to give up.
Day 21 arrived, and 5 of those 6 hatched.
Then, this year, I had 5 refrigerated guinea eggs that I'd left as an enticement to get the guineas to lay more in that spot. 2 different hens went broody on them, but I took them off, and gave them other eggs. Then different hens sat on them while laying eggs, for days. It was very chilly at night, too. Finally, when another hen went broody on them, I just left her there, meaning to swap those out with fresh ones. Then I just left them, deciding to candle after a few days and see if anything was growing. To my surprise, again, there was development. So I let them stay. I hadn't marked the calender when they were started though. A couple of times, some of the eggs had gotten knocked out of the nest, and were stone cold when I found them. I was about to take those eggs and toss them, thinking they were about a week overdue, but not sure. The afternoon I was going to take them out, surprise! There were 2 keets in the nest. By the next morning, all 5 eggs had hatched. One died, probably got crushed somehow, but the other four are fine. Two are now 3 days old, and 2 are 4 days old.
So don't get discouraged by these minor occurrences. If you have healthy birds, and healthy eggs, most of them will survive all kinds of blunders. And be strong healthy stock.
I think sometimes we kill them off trying to be too careful.