The poop in the first picture does appear full of mucus and possibly some blood. I would also treat with Corid. Give a couple of drops of the undiluted Corid liquid to her twice a day as a drench, as well as having her drink the Corid water. I like to dip their beaks into the water to drink for a second, and let them swallow. Unfortunately when baby chicks start showing symptoms like hers, it might be too late to save her, but I would really keep trying. If you get the Corid powder, you can mix 1 1/2 tsp into 2 tsp of water, and get the same concentration of Corid liquid to use a ps a drench.