I'm so sorry about your Silkie. I know you're absolutely devastated by this tragedy. You've identified two possible causes of her death, but there is a third one, and it's more common that people think. And the clue this may be cause of your Silkie's death is the very fact of her dying in the nest. It's called sudden death syndrome.
Sudden death syndrome is caused by calcium deficiency. These deficiencies come about suddenly and may not be noticed until it's too late. Most of us are aware of a calcium deficiency when we pull a very thin shell egg from the nest box or we find a shell-less egg splat on the poop board in the morning. When this happens, we have forewarning that the hen has low calcium reserves and we can then treat her for this with a concentrated calcium supplement.
But if we do not get this warning via an egg with a poor shell, then such a hen may go to lay an egg, and when the egg hits the shell gland to get the shell laid over the membrane, there suddenly is no calcium in the shell gland. So, the hen's body draws heavily on the calcium in her blood, trying to find enough to make a shell.
The problem is that the calcium in the blood is already spoken for, required by the heart to keep beating. The tragic consequence is no calcium left to keep the hen's heart beating and she has a heart attack and dies. This is almost always the cause of death when we find a hen dead on her nest.
To prevent this tragedy, it's important to pay attention to the shell quality of each of our hens' eggs. It's a very simple matter to treat. I use this form of calcium since it's the easiest to digest and absorb.
One tablet each day directly in the beak, whole, not diluted. Do this until egg shell quality is good again. You will prevent not only the tragedy of sudden death syndrome, but egg binding which can be life threatening.
