I had three Silkies, one was older than the other two at 11 weeks, the other two are about 8-9 weeks old now. Last night I noticed the oldest one seemed listless compared to the others. He was fine all day. I pick them all up and look them over every day and he seemed fine a few hours earlier. It was late at night when I last checked them, so I thought he was just sleepy. This morning I noticed he hadn't moved from his spot last night. I picked him up and right away noticed he didn't try to struggle. His head was up and he was alert, but not moving his wings or body. He didn't feel hotter than usual. I didn't want to touch the other two to compare. There was no discharge from the eyes, nostrils or beak, but he had some stuck on diarrhea on his vent. I couldn't tell the colour, it seemed more like clear liquid. I decided to make a quarantine box for him with paper towel so I could have a better look at his poop. I went and got the box ready, it took about 5 minutes. When I went to their pen to put him in the box, he was already dead. It appeared he had had a seizure. He was flipped over on his back, with his head twisted backwards underneath his body and his feet in the air. His whole body (spine) was twisted to one side. He had already begun to stiffen. My big concern is preventing the other two from getting sick, if possible. Right now they're behaving normally and are active. They are in a wire pen with wood shavings for bedding. They were all in the same pen for about a month. I do have another pen I can prepare to move them to, in fact I was already planning on moving them today. But I want to know the best way to disinfect the old and new pens. These pens are indoors. I was thinking of bleach and water, but if anyone has better ideas I'd appreciate the advice. I also want to disinfect their food and water dispensers. I plan to run those through the dishwasher. Is there anything I could treat the remaining birds with, to help prevent them from getting sick as well? I was thinking of a probiotic. I have some organic apple cider vinegar. I also have plain yogourt. Any ideas?