I do believe it's blood. I've seen the red discharge on my other rats. She seems to have a small gash on her nose, I believe it was from a poorly made hopper feeder now. It's been removed. Her food is currently in a bowl until she gets her weight back up. I've put a few from the older litter in to see how mum 2 reacts. I'm wondering if the feeder might be part of her weight loss. If it was hurting her when she went to eat she might not have wanted to eat as much.