I got home from work today and let the girls out to free range until bedtime. They all rushed out as usual to start scratching and foraging. Then when I opened up the coop door to clean the poop board and gather eggs, I was shocked to find one of my Bielefelders dead on the poop board. It happened sometime overnight or in the early morning, because the other birds had pooped on her.She didn't have any external wounds. She was fine yesterday afternoon and evening when I put them up for the night. She laid an egg yesterday. All the other girls are acting normal today, all the poop I scooped looked normal. I treated them all yesterday with Valbazen as a follow up to Wazine 10 days ago. I gave each bird 0.5 ml (or less depending on how much they fought) and she is one of my bigger girls, so definitely didn't overdose her. I saw round worms in poop, but I live in rural Central Florida where it's always warm and humid, with lots of wildlife, so I figured they had more than just one kind. It was also time for the 10 day lice follow up treatment, so they all got dusted with some Dust On powder (approved for poultry and I've used it before on all of them without problems). I then cleaned out the roost and nesting boxes, creating lots of dust which I tried hard to keep away from my girls, then put down fresh pine shavings and sprinkled with more Dust On powder. I tried to call the vet to ask if they could do a necropsy, but they were already closed. I wasn't sure how "fresh" she would need to be for it or that they would even do it, so my daughter and I had a little funeral and I buried her. Could she have reacted to the Valbazen? I can't think of any other reason that would cause an otherwise healthy bird to just drop dead suddenly overnight. She was so sweet and friendly. I am crushed.