one of my17 weeks old roosters seems to be ill. he just lays in the same general spot all day. this has been going on for a couple of days now. i've tried to stand him up but his legs seem to be very weak and he just flops back down to the floor. he's constantly dosing off and at times looks dead. yesterday i wanted to move him outside into the run for some fresh air and i noticed that his vent and surrounding area was covered in dark & bright green runny poop, as if he's just poopin while laying down. i've added electrolytes/vitamins to the water and dipped his beak in there several times. but i'm yet to seem him stand on his own to drink or even eat. does any of this sound familiar to anyone? should i seperate him from the rest of the flock?