3 Dead - plz help!

[BlueEggs4Life]

I'm hoping someone on here has an idea of what is going on in my coop - I found three dead bantam hens today. Everyone else seems fine, no sign of illness that I can detect. These 3 that died seemed fine yesterday. We have had hard rains the past few days but other than that everything has been normal. Anyone have any ideas of what I should be looking for? So sad right now...

 

[BlueEggs4Life]

I've added vitamins to the water today in hopes of preventing any more deaths - any other preventative measures I can take?

 

[nightowl223]

Were they, or are the rest, skinnier than they should be? They may need wormed. If they have a bad infestation of worms, they can literally starve to death.