My husband went out and found an egg with no shell! So I went out and looked, in our barn the one chicken and one rooster, roost at night on the pens which are 5 ft high, they don't bother going in coop. She layer an egg with no shell that broke open on floor of goat pen, then a second which did not break. We feed a egg laying feed, so I'm not convinced it is a lack of calcium. She has only been laying for 2 weeks or so. And about every other day, until she skipped a day or 2 and layer these shell-less ones. 2 days ago I cleaned out the barn with water and vinegar. It took 2 days to dry and so when her egg hit it broke, as there wasn't much hay (husband was helping me) she does have about 6 or 7 nests in her coop that she made. My cousin said that if you take an egg and soak it in vinegar over night that it will turn into what I have-basically. Could the vinegar I used cleaning cause this?