Last night I noticed very watery poop in my 3 wk old black australorp chick. It was clear, like water. Three days ago I know her poop was normal. This morning when I was watching her, she had another poop like water, but a little mucousy...then about 15 mins later had another water poop, but this one had a single streak of mucousy blood in it. She is acting fine, and eating and drinking. She is the same size as all the other 7 chicks. Their brooder is dry and clean, their water is clean and raised off of the bedding, and they are on unmedicated starter/grower (all TSC had). I have offered them plain organic yogurt on several occasions and they want nothing to do with it. I put a Tbsp of Apple Cider Vinegar in their water this morning. Since she still is acting normal, should I wait to see what happens? or should I try to find some Sulmet and start them on that?