I've had chickens for ten years and never before have I lost so many birds to disease. In past half a year I've lost two white silkie hens, one with no symptoms other than extreme emaciation, the other with abdominal swelling. I've lost a Crevecour hen who seemed fie one day, ruffled and dumpy the next, and by the evening she was dead after apparent respiratory distress.

Now I have a Sebright rooster who is sick (possible infection) and have just discovered my black silkie rooster dead after seeing him alive and maybe a little mopey but well an hour ago. He has a large yellowish scab on his belly, and his vent looks oddly milky and and ha some dark reddish prtrusion which might just be guts poking out after death. But he's so recently dead he was still limp when I found him a moment ago.

Does anyone have any idea what I might be dealing with here? Is my whole flock at risk at this point? Or is just a string of bad luck?