How can I help a very sick finch?

I would bring him into the warmth, but these little chaps don't survive long once they are ill as they tend to hide illness until near to the end . can you try and find any other local breeders who may have a little soluble antibiotic to drip into his beak, or poultry breeders who may have a drop of Baytril or something similar. GOOD LUCK,