help poorly cockerel

my cockerel was limping so i took him to the vet,who diagnosed BUMBLEFOOT he had a huge sore on his foot so i poulticed it and gave prescribed antibiotics and was told not to be confident he will be ok,it is likely he will need to be put to sleep!!!,
He seems well in himself and although the sore is looking better,i dread taking him back to the vet,
Can anyone help with advice? is there something i can give him or do? i dont want to lose him,he is a very large boy who is very well behaved and gentlemanly and looks after his ladies so well.

Thank you NEW SHOOT i will go there now!