We were at a friend's house today and they had a 2 week old Guinea that was sick. It could not walk, legs kept slipping out from under it and going off to the side. Of course my son and friend's daughter had a sick ward set up before I even knew what was going on, clearing its' pasty butt and feeding it vitamin e, electrolytes and probiotics from a Q tip. I had my kids get straight in the bath and threw their clothes and shoes in the wash. No one has been in the room where our brooder is. What else should I do in case this was Marek's? Any other ideas what could cause these kind of symptoms? Bird would drink a little but not eat. It did poop once they cleaned the vent. Seemed neurological to me but hard to tell as I'm new to chickens. As far as they know the bird was fine yesterday.