This hasn't been a good week and I'm looking for advice. On the 4th we lost a Polish to vent prolapse. Yesterday we found a Production Red swollen below her vent and straining. Yesterday afternoon I found a Polish in the nest box looking dead with wet vent area, some yellow - I assumed yolk on her head and butt. Both of them yesterday went into the dog crate after sitting in warm water and having their vents checked. This morning I found this from my Polish girl. I have two containers of Oyster shell in the coop that does get eaten. Do I also need to add it to their feed? They free range more than half of the day. Could this have caused the other hen's death and my Red who still isn't acting right?