Whenever I see respiratory infection I think of secondary infection caused by something else like cocci or worms. Seeing as your chick is on the ground, I would take it inside and treat it for both cocci and worms and see how it reacts.
I did have one chick last year that was doing something similar to yours that I finally gave up on. Brad Legg told me to cull it, I couldn't do that and I couldn't keep making it a pin cushion with all the injections either, I had given it multiple round of every med I could think of. I finally gave it to @thndrdancr for homeopathic treatment. I believe the last time she mentioned its condition that she said it may be a birth defect which is what Brad had suggested as well.
I have a video of it, but I am not savvy enough to post it.