I have a flock of young chickens the oldest are only 1.5 years old and they are getting sick. It starts with their lower eyelids swelling up then they seclude themselves from the group and they have very greenish diaherrea. They tuck their necks in and just perch and dont move then some have been having neck twiches, almost like a muscle spasm. Within a few days of these symptoms they have been dying. I heard that UltraViolet lights can kill some chicken diseases, but not sure if I should buy a blacklight or a Plant light, neither lists that it is UV. Please help. Tell me if you have used the light or have had chickens with the same symptoms. Thank you!