Please understand that I mean this in the nicest way possible, really, I do. Okay... Don't second guess yourself or beat yourself up, 'cause sometimes this is how we learn, I know it's how I learn. One thing I've learned in the last two years is that there is no downside to worming a sick one...
So sorry for your loss, I know all too well how hard it is to lose one. Did you know that chicken necropsies are free in California?
http://www.vetmed.ucdavis.edu/cahfs/lab_tests/index.cfm
-Kathy