Excessive salvia or mucus coming out of lethargic baby chick?!

[Chicksgowild]

I have a 4-5 week old baby chick who is lethargic, has ruffled feathers, and hunched over. Her hocks are purplish. I checked under her wings and they are also purplish. I will provide some pictures. Something that I also noticed is that saliva comes out and sometimes like vomits out food? The food comes out with saliva/mucus. I do not know what is going on. It also seems as if food gets stuck in her mouth. Food gets stuck at the top of her beak inside and at the top of the beak at the bottom (in the mouth). I open her beak, and she sometimes has this sticky saliva or mucus + some food and I have to clean it out with a cotton swab. I try to pick her up and when I do she opens her beak like if she is gasping for air. I know something is going on, I just don't know what. What do you think it is? Here are some pictures. I recorded 2 videos, upload led on YouTube. Please watch them so that you can see what I mean.