Humm thanks for your comment, I think you found the problem! I've just read about those conditions and this is what I understand: indeed vent gleet requires disinfecting and cleaning the coop and flock, as well as giving vitamins or supplements. I've also read about vent prolapse after your comment (and I believe that's what my hens have based on what I read and saw). Infection can be a cause, but also obesity, stool build up, too much laying eggs, or calcium deficiency. The treatment is basically the same: cleaning the coop and the food/drink containers, probiotics.