5 day old EE pullet was the most happy and inquisitive out of all my 4 other week old babies. This morning she started shaking her head and sneezing. There was no nasal discharge, eyes and nose were clear. Her crop was not full. She was active, eating, drinking pure unsalted well water with apple cider vinegar (ACV) and acting normal. I did notice that she was not pooping like the others. Minimal amounts and infrequently and only the white topped kind. I just went to check on her and while I was watching she convulsed three times and died. I need to mention she was purchased from a reliable feed store that had just received their shipment a few hours before I went in. Do I need to do something to the other 4 girls who are acting normal (at the moment)?