help - closed eye and swallen face - cockerel

[chickengr]

I treated all my flock last week but as cockerels don't eat and drink a lot they probably didn't take enough antibiotics. one has been recovering in the house, looks fine at the moment. I have just found another one with his left eye closed (he can open it), the left part of his face swallen and a lot of mucus in his left nostril. he ate a bit and drank some water. but he is falling down rapidly. I had to chase him to catch him and put in the house. he looks like dying. what can I do to help him?

 

[chickengr]

I forgot to say there is no bad smell. he just looks very tired and does not want to eat or drink. I gave him some antibiotic with a syringe.