I have about 8 baby chicks ranging in age from 1-3 weeks. Yesterday one of my baby chicks started to have what looked like seizures. She would start to scratch at her belly and then fall over and roll into a ball several times while twitching. I separated her for a while and held her while making her drink water and eating some yogurt with vitamin E mixed in and then added her back in with the rest of the flock. She seems to be doing okay but still has these fits. I've uploaded a video of it below. She starts to do it about 50 seconds into the video. What is this?