Omg!
You say you tried to move it & the hock bled?
That sounds like a serious fracture or break near the hock joint. When you tried to move it, did you notice perhaps a splinter of bone briefly popping through the skin causing the bleed?
It sounds really serious, whatever it is. ..
Is it possible to take 3 photos at different angles around the leg joint so I can get a good idea of the situation & try and advise you?
I’m really sorry, it sounds like the pet shop was not following standards. That chick should have recieved medical attention immediatly or culled, not been out on sale.
You did a kind thing buying it, goodness knows how much it suffered. I would think about reporting the pet shop, they should not be selling sick / injured animals at all by law.