My chickens are having very dark liquidy poo. Very runny, liquid poo. They are kept in my garage right now until the coop and run is finished, on pine shavings in huge cardboard boxes. They are fed Chick crumbles and chick grit, and lots of water. I started to put some ACV in their water but then noticed the runny poo and thought maybe it was the ACV or I was using too much? So I stopped, but their poo is still very runny. It's hard to keep their pen clean, the poo is all over their roosts and is very dark brown like melted chocolate. Also, my two light brahma girls are getting messy One has it on her breast feathers. They like to perch on the side of their boxes when I visit them and one poo'd and it Splashed! onto my shoe! what the heck. It also smells awful. Thought maybe it's cecals but it seems pretty frequent. Any advice is much appreciated. They are 7 weeks old, and no blood. They are happy, full of energy and eating/drinking fine. No treats right now, only feed and grit.