I checked on my chickens around 4:00 PM to see if we had any late eggs. I "tuck" them in every night to make sure everyone is okay. At 7:00 PM I found my RIR panting and lethargic. Immediately separated her from the others and have her in a carrier in the sun room. Heard banging went to check on her looks like she was seizing. Nothing to indicate an illness. No discharge, no diarrhea, layed this morning, ate well. This is so fast and I really think she'll die. What could it be and am I now going to watch the rest of my flock die?