Personally, i would never keep my goats in the same area as my chickens. Too easy for the goats to be playing and accidentally step on a chicken. This morning i had my one standard hen out in the goat area free-ranging while i moved her food and water out of the shed to her pen. My little Nigerian Dwarf, Tinker, kept trying to head-bunt her. She was just playing, but if she had connected she could have done some damage. So you need to be careful.
i also second JJthink's suggestion. You absolutely have to get a necropsy done to be sure of what is going on. Go to this link: https://www.backyardchickens.com/forum/viewtopic.php?id=40141 and you can follow the links to locate your local state vet. When i needed help, my state vet referred me to our local university who provides free necropsies. It has been a wonderful resource for me when i have lost birds for no apparent reason.
i also second JJthink's suggestion. You absolutely have to get a necropsy done to be sure of what is going on. Go to this link: https://www.backyardchickens.com/forum/viewtopic.php?id=40141 and you can follow the links to locate your local state vet. When i needed help, my state vet referred me to our local university who provides free necropsies. It has been a wonderful resource for me when i have lost birds for no apparent reason.