picked up some young RIR from a neighbor and kept them quarantined for several days. all looked healthy and were very healthy and active during this time period. yesterday, i turned them out into the fenced in pasture with the others. all seemed fine until this morning, one of the birds was just sitting on the ground not moving. i bumped her to get her moving, but she just sat there. i finally moved her to another quarantine area after about an hour. she's around 20 weeks old ... any theories, or is this just one of those things?