I'm really worried about some of my new three day old silkie chicks. Most of them are fine, but I've noticed that one of them keeps picking at his butt and when I went to clean off his pasty butt I noticed that he had a big red sore on the top of his vent. He won't stop picking at it even though I cleaned it up. I don't know how to stop him or what to do. I also noticed that he and a couple other chicks seem to be straining to poop. I don't know what's wrong with them! Can anyone help me?