We have 2 week old chicks and they were all doing fine until last night, one of them started squeeking and gasping for air. It was shaking it's head like it was trying to clear it's nose. We are feeding them medicated chick starter and little bits of yogurt and egg. I put 2-3 drops of Organic Apple cider vinegar in their water. We just got probiotics from feed store and are going to try that in their water. We moved the heat lamp up a foot because I thought maybe it was getting to warm and we also separated it from the other chicks. It's poop is wetter than I have seen before, brown only in color and somewhat still in solid form. Any advice?