What you described was our experience mid March! Our broody recieved 7 chicks and at 1st still seemed to be in a broody daze. My thoughts were uh oh - maybe she can just serve as a heater as the chicks were already finding food & water and then going back under her. By day 2 or 3 she came around...
It's been 3 yrs since last post but I'm experiencing the same with a Lavender Orpington TSC. Hers seems neurological as she sometimes shakes or falls over. She eats and keeps up with Mum and 6 siblings. Seems bright and alert but does rest more. Minimal wing feathering and just a stub of a tail...