one of my younger hens she is about 20-22 weeks old started acting funny day before yesterday she is eating drinking and poops are normal color but she is very disoriented and acts like she cant stand up or walk without almost falling over, I seperated her from the flock and she is in the chicken infirmary with a low watt heat lamp but no improvement any suggestions as to what might be ailing her or is it time to cull her? and if it is time to cull what is the most humane way to do it? thanks