Swollen hock in chick

[alhintz]

We had a hatch a couple of days ago and four of the eleven chicks ended up with leg problems (which I am guessing is due to temperature fluctuations). All four seem to be have splayed legs to some degree or another as well as crooked toes, and all have on hobbles. One of the chicks died this morning, and all the others seemed to be doing better but now one of them seems to be resting on it's hock which is becoming swollen and chaffed.

I would greatly appreciate any advice on what I should do?