Sorry for your losses. I’m unsure if you can get a necropsy in Hawaii. I would try checking each chicken to see if they are losing weight. Offer some cooked egg or tuna occasionally to see if they are eating. If one is weak, mix a quart of water with a tsp of sugar and small pinch of salt, which can help as electrolytes. If the grocery sells Pedialyte for babies, that works well too. Mold is toxic to chickens, so don’t let them eat around compost beds. You could be dealing with worms, or a disease. The symptoms of a sick chicken may help us help you.