Help! I have had chickens for about 5 springs, 2 of my chickens are original flock and the rest of the 8 are 2 springs. For the last month we keep getting a nasty smelling egg among other good eggs, the coops is clean, the water is fresh and clean, the food is the same food we have used for 4yrs. We haven't been giving them anything new or different and there are no weeds in the run area. None of the chickens are acting any different, not sick at all. We threw out all eggs we had and then using 3 fresh ones we smelled each egg, no bad smell on the outside shell, we cracked open each egg, inside smelled nice and fresh, we soft fried them and carefully popped the yolk and 1 out of the 3 smelled bad. Not a sulphuric rotten egg smell, more like chicken poop. What can be causing it? Could age of the hen a factor?